N-CSRS 1 a06-16769_3ncsrs.htm CERTIFIED SEMI-ANNUAL SHAREHOLDER REPORT

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number			811-01829

Columbia Acorn Trust
(Exact name of registrant as specified in charter)

One Financial Center, Boston, Massachusetts					02111
(Address of principal executive offices)					(Zip code)

James R. Bordewick, Jr., Esq. Columbia Management Advisors, LLC One Financial Center Boston, MA 02111
(Name and address of agent for service)

Registrant’s telephone number, including area code:				1-617-426-3750

Date of fiscal year end:	December 31, 2006

Date of reporting period:		June 30, 2006

Form N-CSR is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission to stockholders of any report that is required to be transmitted to stockholders under Rule 30e-1 under the Investment Company Act of 1940 (17 CFR 270.30e-1). The Commission may use the information provided on Form N-CSR in its regulatory, disclosure review, inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-CSR, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-CSR unless the Form displays a currently valid Office of Management and Budget (“OMB”) control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. § 3507.

Item 1. Reports to Stockholders.

Columbia Management_®

Look inside for details on the 2006 Columbia Acorn Funds Annual Shareholder Information Meeting.

Columbia Acorn

Family of Funds

Class Z Shares

Semiannual Report

June 30, 2006

n Columbia Acorn Fund

n Columbia Acorn International

n Columbia Acorn USA

n Columbia Acorn International Select

n Columbia Acorn Select

n Columbia Thermostat Fund

^{Managed by Columbia Wanger Asset Management, L.P.}

NOT FDIC-INSURED

May Lose Value

No Bank Guarantee

Please join us at the

2006

Annual Shareholder Information Meeting

September 26, 2006
9 a.m. – 10 a.m. Central time

Chase Auditorium
(formerly Bank One),
Plaza Level
38 South Dearborn Street
Chicago, IL 60602

Refreshments will be served prior to the meeting.

Please RSVP by September 19 by calling
(800) 922-6769

( Not able to make it but interested in hearing from your portfolio managers?

This year you can call to listen to an audio recording of the meeting. The recording will be available by 3 p.m. Central Standard Time on September 26 and can be accessed using the following number and pass code.

Toll Free dial-in number to listen to a recorded replay of the 2006 meeting: (888) 613-4193

Pass code to enter when calling: 4120362

8Questions? Email Us!

We'd love to hear from you! Email your questions to us at the following email address. Please DO NOT send questions regarding your personal account to this address. Questions regarding your account should be directed to our shareholder services representatives at (800) 922-6769. Your questions will help our portfolio managers in preparing their presentations. Answers to your questions will be made available soon after the meeting date.

Email questions to:
dg.227w-meeting_questions@bankofamerica.com

For directions and parking information, see the inside back cover of this report.

Columbia Acorn Family of Funds Semiannual Report 2006

Table of Contents

Performance At A Glance					2

Squirrel Chatter II: Understanding our Team Approach					3

Understanding Your Expenses					6

Columbia Acorn Fund

In a Nutshell					8

At a Glance					9

Major Portfolio Changes					20

Statement of Investments					22

Columbia Acorn International

In a Nutshell					10

At a Glance					11

Major Portfolio Changes					34

Statement of Investments					36

Portfolio Diversification					41

Columbia Acorn USA

In a Nutshell					12

At a Glance					13

Major Portfolio Changes					42

Statement of Investments					43

Columbia Acorn International Select

In a Nutshell					14

At a Glance					15

Major Portfolio Changes					49

Statement of Investments					50

Portfolio Diversification					53

Columbia Acorn Select

In a Nutshell					16

At a Glance					17

Major Portfolio Changes					54

Statement of Investments					55

Columbia Thermostat Fund

In a Nutshell					18

At a Glance					19

Statement of Investments					76

Statement of Assets and Liabilities					77

Statement of Operations					78

Statement of Changes in Net Assets					79

Financial Highlights					81

Notes to Financial Statements					82

Columbia Acorn Family of Funds

Statements of Assets and Liabilities					60

Statements of Operations					61

Statements of Changes in Net Assets					62

Financial Highlights					66

Notes to Financial Statements					70

Management Fee Evaluation of the Senior Officer					86

Columbia Acorn Family of Funds Information					91

>2006 Mid-Year Distributions

The following table details the Funds' mid-year distributions. The record date was June 5, 2006. The ex-dividend date was June 6, 2006 and the payable date was June 7, 2006.

	Short-term Capital Gains		Long-term Capital Gains		Ordinary Income		Reinvestment Price
Columbia Acorn Fund	None		$	0.3132		None	$	29.24
Columbia Acorn International	None		$	0.5514	$	0.0775	$	37.43
Columbia Acorn USA	None		$	0.1016		None	$	27.40
Columbia Acorn International Select	None			None	$	0.0496	$	23.10
Columbia Acorn Select	$	0.0862		None	$	0.0492	$	23.73
Columbia Thermostat Fund	$	0.0046	$	0.2367	$	0.0467	$	12.47

The discussion in this report of portfolio companies is for illustration only and is not a recommendation of individual stocks. The information is believed to be accurate, but the information and the views of the portfolio managers may change at any time without notice and the portfolio managers may alter a Fund's portfolio holdings based on these views and the fund's circumstances at that time.

>Performance At A Glance Class Z Average Annual Total Returns through 6/30/06

	NAV on 6/30/06		2nd quarter*			Year to date*			1 year			3 years			5 years			10 years			Life of fund
Columbia Acorn Fund (6/10/70)	$	29.49		-3.73	%		5.81	%		16.44	%		21.94	%		12.31	%		14.97	%		16.29	%
Russell 2500				-4.34	%		6.32	%		13.53	%		19.16	%		9.65	%		11.13	%		NA
S&P 500				-1.44	%		2.71	%		8.63	%		11.22	%		2.49	%		8.32	%		11.79	%
Lipper Small-Cap Core Funds Index				-4.76	%		6.30	%		14.52	%		18.59	%		9.13	%		10.03	%		NA
Lipper Mid-Cap Core Funds Index				-3.29	%		4.31	%		12.07	%		16.41	%		7.25	%		10.42	%		NA
Columbia Acorn International (9/23/92)	$	37.58		-1.11	%		14.27	%		35.18	%		32.82	%		15.42	%		11.63	%		13.74	%
S&P/Citigroup EMI Global ex-US				-1.70	%		10.57	%		31.22	%		31.90	%		18.28	%		8.46	%		9.60	%
MSCI EAFE				0.70	%		10.16	%		26.56	%		23.94	%		10.02	%		6.39	%		8.17	%
Lipper Int'l Small-Cap Funds Index				-2.72	%		10.26	%		31.71	%		32.29	%		17.72	%		11.64	%		NA
Columbia Acorn USA (9/4/96)	$	27.52		-4.39	%		2.19	%		9.45	%		19.51	%		9.58	%					14.04	%
Russell 2000				-5.02	%		8.21	%		14.58	%		18.70	%		8.50	%					9.63	%
Lipper Small-Cap Core Funds Index				-4.76	%		6.30	%		14.52	%		18.59	%		9.13	%					10.65	%
S&P 500				-1.44	%		2.71	%		8.63	%		11.22	%		2.49	%					8.68	%
Columbia Acorn Int'l Select (11/23/98)	$	23.16		0.48	%		12.83	%		30.10	%		27.83	%		11.83	%					12.25	%
S&P/Citigroup World ex-US Cap Range $2-10B				-0.61	%		10.29	%		31.69	%		30.15	%		15.80	%					11.52	%
MSCI EAFE				0.70	%		10.16	%		26.56	%		23.94	%		10.02	%					6.04	%
Lipper International Funds Index				-0.52	%		9.30	%		27.26	%		23.15	%		10.14	%					7.24	%
Columbia Acorn Select (11/23/98)	$	23.87		-2.22	%		5.43	%		17.28	%		15.89	%		11.75	%					14.46	%
S&P MidCap 400				-3.14	%		4.24	%		12.98	%		18.14	%		9.30	%					11.95	%
Lipper Mid-Cap Growth Index				-4.64	%		4.40	%		15.46	%		15.12	%		2.64	%					6.86	%
S&P 500				-1.44	%		2.71	%		8.63	%		11.22	%		2.49	%					2.74	%
Columbia Thermostat Fund (9/25/02)†	$	12.53		-0.55	%		2.56	%		6.65	%		9.08	%								10.83	%
S&P 500				-1.44	%		2.71	%		8.63	%		11.22	%								14.41	%
Lehman Brothers U.S. Credit Intermediate Bond Index				0.06	%		-0.47	%		-0.61	%		1.83	%								3.97	%
Lipper Flexible Portfolio Funds Index				-1.30	%		3.07	%		10.01	%		10.40	%								12.58	%

*Not annualized.

Performance shown here is past performance which cannot guarantee future results. Current performance may be higher or lower. The investment return and principal value of an investment in a Fund will fluctuate so that Fund shares, when redeemed, may be worth more or less than their original cost. Performance changes over time. Visit columbiafunds.com for daily and month-end updates. Net asset value (NAV) returns do not include sales charges or contingent deferred sales charges (CDSC). Class Z shares are sold only at NAV with no 12b-1 fee. Class Z shares have limited eligibility and the investment minimum requirement may vary. Please see the Funds' prospectus for details.

Performance may reflect any voluntary waivers or reimbursements of fund expenses by the advisor or its affiliates. Absent these waivers, or reimbursement arrangements, performance results may be lower.

†A "fund of funds" bears its allocable share of the costs and expenses of the underlying funds in which it invests. Such funds are thus subject to two levels of fees and potentially higher expense ratio than would be associated with an investment in an investment fund that invests and trades directly in financial instruments under the direction of a single manager.

Description of indexes: S&P 500 is a broad, market-weighted average of U.S. blue-chip company stock performance. S&P MidCap 400 is a broad market-weighted index of 400 stocks that are in the next size/tier down from the S&P 500. Russell 2000 is a market-weighted index of 2000 smaller U.S. companies, formed by taking the largest 3,000 companies and eliminating the largest 1,000. Russell 2500 is the smallest 2,500 U.S. companies from this same group. S&P/Citigroup EMI Global ex-US is the bottom 20% of institutionally investable capital of developed and emerging countries, selected by the index sponsor, outside the U.S. MSCI EAFE is Morgan Stanley's Europe, Australasia and Far East Index, a widely recognized international benchmark that comprises 20 major markets in proportion to world stock market capitalization. S&P/Citigroup World ex-US Cap Range $2–10B is a subset of the broad market selected by the index sponsor representing the mid-cap developed market excluding the U.S. Lipper Indexes include the largest funds tracked by Lipper, Inc. in the named category. Lipper Mid-Cap Growth Index, 30 mid-cap growth funds; Lipper Mid-Cap Core Funds Index, 30 mid-cap core funds; Lipper International Funds Index, 30 largest non-U.S. funds, not including non-U.S. small-cap funds; Lipper International Small-Cap Funds Index, 10 largest non-U.S. funds investing in small-cap companies, including Columbia Acorn International; Lipper Small-Cap Core Funds Index, 30 largest small-cap core funds, including Columbia Acorn Fund. Lipper Flexible Portfolio Funds Index is an equal dollar-weighted index of the 30 largest mutual funds within the Flexible Portfolio fund classification, as defined by Lipper. The Lehman Brothers U.S. Credit Intermediate Bond Index is the intermediate component of the U.S. Credit Index. The U.S. Credit Index includes publicly issued U.S. corporate and foreign debentures and secured notes that meet specified maturity, liquidity, and quality requirements. All indexes are unmanaged and returns include reinvested distributions. It is not possible to invest directly in an index.

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>Squirrel Chatter II: Understanding our Team Approach

In recent Squirrel Chatters, I've discussed drivers to the historically strong, long-term performance of the Columbia Acorn Funds.¹ First, I addressed our style—investing in small- and mid-cap stocks using a Growth-at-a-Reasonable-Price discipline. Next, I covered our analytical process—how we research, value and track our investments. In this final part of the series, I cover why we need a large analyst team, how we hire and train analysts, and how we empower and evaluate them.

A Large Team Provides Full Market Coverage

Investment management consultants and the financial press often express concern when small- and mid-cap funds become large. For years, many postulated that small-cap managers would stop outperforming their benchmarks once their assets exceeded $1 billion. Columbia Acorn Fund hit $1 billion in 1991. We agree that small-cap funds cannot grow indefinitely. However, historically we believe we have succeeded in managing assets far above the supposed $1 billion "limit" by employing a large analyst team.²

Based on our observations, it seems that many small- and mid-cap portfolios are managed by one or two managers, often without the help of additional analysts. (Their investment adviser may employ lots of other analysts, but they usually are focused on large-cap stocks). Many investment professionals have expertise in just a few industries or geographic regions. Consequently, small management teams tend to focus their funds on relatively small sectors of the market. When their sectors are hot, they can achieve astounding performance, and their funds can grow rapidly. We've seen this happen to some funds during technology and energy booms in the past. When the sector turned, however, many of the funds crashed and burned.

We've taken a different approach. At Columbia Wanger Asset Management, we have built a team of 21 analysts (including our portfolio managers, who are also analysts), covering virtually all important industries and geographic regions. We are not aware of any other investment firm with so many analysts focusing solely on small- and mid-cap stocks. Broad coverage can be crucial especially near market turning points. For instance, when many competitors concentrated their research and their portfolios in technology, media and communications stocks in 2000, a broader perspective led us to U.S. real estate stocks that appeared cheap at the time. We added REITs to Columbia Acorn Fund, which helped to boost fund performance for several years.

Hiring Good Analysts

In order to maintain and grow a large analyst team, Columbia Wanger Asset Management is in a perpetual hiring mode. Our directors of research, Rob Mohn on the domestic side and Zach Egan on the international side, are always looking for good people.

We require analyst candidates to have what we call a "tool kit of knowledge." Accounting, finance and economics skills are required for all analysts. In addition, cultural knowledge and language skills are needed for our international analysts. Accounting is mentioned first because we believe accounting is essential in valuing companies. We once had an analyst candidate tell us during an interview, "Some people think accounting is important for securities analysts, but I don't." Well, we do. That candidate is not a part of our investment team.

We also want candidates to be stock nuts (quite appropriate for the Columbia Acorn Funds). By that we mean people who are thinking about stocks day and night. We envision an ideal candidate as having a stack of annual reports next to the most comfortable seat at home. The candidate should be constantly on the lookout for investment opportunities, even when strolling down

the street. If parking lots are raising their rates, or if a restaurant chain has people lined up out the door, a true stock nut will see these as possible investment opportunities.

Academic and professional credentials, combined with investment experience listed in a candidate's resume, provide evidence of a tool kit and stock nut. Discerning our other important requirement—an economic mind—requires face time. By economic mind we mean having the ability to recognize what may be a good business over the long term and how a changing environment could affect the business. Some people seem to have that shrewdness by nature while others seem incapable of learning it.

Unless we lose an experienced analyst who follows a crucial area, we prefer to hire analysts with modest prior experience. More experienced analysts may have developed bad habits elsewhere that could be very difficult to change.

Mentoring New Analysts

We don't have a formal training program for analysts. Instead, our senior analysts mentor newer analysts. Typically, as a senior analyst becomes overburdened we "hive off" a segment of his or her coverage area, and hire a new analyst to follow it. The new analyst then inherits some stocks to follow.

As a new analyst begins to cover inherited stocks, the mentor has him or her pursue the information, valuation and time horizon edges that we discussed last quarter. The two analysts may conduct a few management meetings and attend a few conferences together so they can compare notes and the mentor can help the new analyst adopt our process and style.

We expect our analysts to properly distill, interpret and communicate information. Our analysts need to distill the massive amounts of information down to the most crucial variables. They need to see through public relations "spin" provided by companies and correctly interpret fundamentals. For example, when a company claims that it "hit earnings targets" a few weeks after it lowered those targets, our analysts can't conclude that things are fine. "Disappointing quarter, as preannounced" is a more appropriate report headline. Likewise, some brokerage firm analysts tend to "adjust" earnings estimates when business is poor. Our analysts need to communicate with words describing direction and magnitude, such as "trim" or "slash." Finally, some companies and analysts may low-ball estimates so they can raise them later, creating good news. We want unbiased estimates from our analysts, which in turn should facilitate better decisions.

Empowering and Evaluating Analysts

Many investment firms have their analysts provide information and make recommendations and have their portfolio managers make decisions. In this traditional structure, accountability is often lacking. Analysts want credit for good recommendations, whether purchased or not, and tend to forget poor recommendations, especially those that were rejected. Portfolio managers tend to believe their decisions drove performance when performance was good, but tend to blame analysts when performance was bad.

Due to the size of our flagship funds,³ the quality of our analysts, our desire for accountability, and our belief that our analysts understand their stocks better than our portfolio managers do, Columbia Acorn Fund and Columbia Acorn International senior analysts have authority to buy and sell individual stocks. Portfolio managers and mentors provide quick approval for reasonable transactions proposed by newer analysts. Portfolio managers also make strategic decisions, including industry and country weightings.

We consider our investment process to be crucial to our success, and for newer analysts we first focus on proper implementation of our proven process. Over time, results matter. We carefully track performance of our analysts' holdings and compare actual performance to analyst benchmarks comprised of their coverage areas' performance. Analysts' job one is to beat their benchmarks. Job two is to forecast whether their areas are likely to outperform and to accurately recommend weightings for their areas in the Funds. Successful analysts are highly rewarded.

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I hope you have found this series on our investment process to be informative. Over the years we've provided much of this information during our annual shareholder meetings and thought it may be of interest to all shareholders. We believe our approach has driven our historically strong long-term track record. We can't expect to outperform our benchmarks every year, but we do intend to continue to work hard and stay true to our time-tested approach.

CWAM News

We are pleased to announce two additions to our analyst team. Gregory Pinsky joined our domestic team, adding to our research of industrial goods, services and materials. His coverage areas include employment services (temporary help and recruiters), waste management and the business services industry. Prior to joining Columbia Wanger Asset Management, Greg was an equity investment analyst at T. Rowe Price Associates. A Certified Public Accountant, Greg received his MBA from the University of Chicago and his bachelor's degree in economics from The Wharton School of the University of Pennsylvania.

Jeannie Cheung joined our international analyst team to cover China, Taiwan and Korea. She is currently employed by Columbia Wanger Asset Management's parent company, Bank of America, in Hong Kong, to provide research to Columbia Wanger Asset Management. Jeannie has worked as an equity analyst since 1991 and was most recently director of China research for Credit Suisse (Hong Kong). Jeannie has a CFA designation and has also completed a master's degree in finance and investment at the University of Exeter in the United Kingdom.

Beginning this quarter, our shareholder reports have a new look. The Columbia Acorn Funds' quarterly reports have adopted a similar look to other funds distributed by Columbia Management.

Charles P. McQuaid

President and Chief Investment Officer
Columbia Wanger Asset Management, L.P.

Past performance is no guarantee of future results.

Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies.

¹ As of June 30, 2006 Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select and Columbia Acorn Select all beat their benchmark indexes since inception. See Page 2 for full performance information. Columbia Thermostat Fund performance since inception through June 30, 2006 was between the S&P 500 and the Lehman Brothers U.S. Credit Intermediate Bond Index, which is in line with the Fund's investment objective.

² Our understanding of the competing small-cap analyst team size is based on conversations we have had with competitors and information provided by third-parties who report on the fund industry.

³ As of June 30, 2006, Columbia Acorn Fund had $17.9 billion in total net assets. It owned 415 stocks, 334 domestic and 81 foreign. Columbia Acorn International had $3.6 billion and invested in 173 stocks.

The views expressed in Squirrel Chatter II are those of the author. These views are not guarantees of future performance and involve certain risks, uncertainties and assumptions that are difficult to predict so actual outcomes and results may differ significantly from the views expressed. These views are subject to change at any time based upon economic, market or other conditions and the respective parties disclaim any responsibility to update such views. These views may not be relied on as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied on as an indication of trading intent on behalf of any particular Columbia Acorn Fund. References to specific company securities should not be construed as a recommendation or investment advice.

>Understanding Your Expenses

As a Fund shareholder, you incur two types of costs. There are transaction costs, which generally include sales charges on purchases and may include redemption or exchange fees. There are also ongoing costs, which generally include investment advisory fees, Rule 12b-1 fees and other Fund expenses. The information on this page is intended to help you understand your ongoing costs of investing in the Columbia Acorn Funds and to compare these costs with the ongoing costs of investing in other mutual funds.

Analyzing your Fund's expenses

To illustrate these ongoing costs, we have provided examples and calculated the expenses paid by investors in the Class Z shares of the Columbia Acorn Funds for the last six months. The information in the following table is based on an initial investment of $1,000, which is invested at the beginning of the period and held for the entire period. Expense information is calculated two ways and each method provides you with different information. The amount listed in the "Actual" column is calculated using each Fund's actual operating expenses and total return for the period. The amount listed in the "Hypothetical" column assumes that the return each year is 5% before expenses and then applies each Fund's actual expense ratio for the period to the hypothetical return. You should not use the hypothetical account values and expenses to estimate either your actual account balance at the end of the period or the expenses you paid during the reporting period. See the "Compare with other funds" information for details on using the hypothetical data.

>January 1, 2006 – June 30, 2006

	Account value at the beginning of the period ($)				Account value at the end of the period ($)				Expenses paid during period ($)				Fund's annualized expense
Class Z Shares	Actual		Hypothetical		Actual		Hypothetical		Actual		Hypothetical		ratio (%)*
Columbia Acorn Fund		1,000.00		1,000.00		1,058.07		1,021.17		3.73		3.66		0.73
Columbia Acorn International		1,000.00		1,000.00		1,142.67		1,020.13		4.99		4.71		0.94
Columbia Acorn USA		1,000.00		1,000.00		1,021.92		1,019.98		4.86		4.86		0.97
Columbia Acorn International Select		1,000.00		1,000.00		1,128.34		1,018.40		6.81		6.46		1.29
Columbia Acorn Select		1,000.00		1,000.00		1,054.30		1,020.03		4.89		4.81		0.96
Columbia Thermostat Fund		1,000.00		1,000.00		1,025.54		1,023.55		1.26		1.25		0.25

Expenses paid during the period are equal to each Fund's annualized expense ratio, multiplied by the average account value over the period and then multiplied by the number of days in the Fund's most recent fiscal half-year and divided by 365.

Had the Investment Adviser and/or Transfer Agent not reimbursed/waived a portion of expenses, total return would have been reduced.

It is important to note that the expense amounts shown in the table are meant to highlight only ongoing costs of investing in the Funds and do not reflect any transactional costs, such as sales charges, redemption or exchange fees. Therefore, the hypothetical examples provided may not help you determine the relative total costs of owning different funds. If these transactional costs were included, your costs would have been higher.

Columbia Thermostat Fund's expenses do not include fees and expenses incurred by the Fund from the underlying portfolio funds.

*For the six months ended June 30, 2006.

Compare with other funds

Since all mutual funds are required to include the same hypothetical calculations about expenses in shareholder reports, you can use this information to compare the ongoing cost of investing in the Funds with other funds. To do so, compare the 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of other funds. As you compare hypothetical examples of other funds, it is important to note that hypothetical examples

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are meant to highlight the continuing costs of investing in a fund and do not reflect any transactional costs, such as sales charges or redemption or exchange fees.

Estimating your actual expenses

To estimate the expenses that you paid over the period, first you will need your account balance at the end of the period:

• For shareholders who receive their account statements from Columbia Management Services, Inc., your account balance is available online at columbiafunds.com or by calling Shareholder Services at (800) 922-6769.

• For shareholders who receive their account statements from their brokerage firm, contact your brokerage firm to obtain your account balance.

1. Divide your ending account balance by $1,000. For example, if an account balance was $8,600 at the end of the period, the result would be 8.6.

2. In the section of the table titled "Expenses paid during the period," locate the amount for your Fund. You will find this number is in the column labeled "Actual." Multiply this number by the result from step 1. Your answer is an estimate of the expenses you paid on your account during the period.

Columbia Acorn Fund

>In a Nutshell

Performance data quoted represents past performance and current performance may be lower or higher. Past performance is no guarantee of future results. The investment return and principal value of an investment in the Fund will fluctuate so that shares, when redeemed, may be worth more or less than the original cost.

Visit columbiafunds.com for daily and most recent month-end performance updates.

Columbia Acorn Fund fell 3.73% in the second quarter, modestly outperforming the small-cap Russell 2500 Index while underperforming the large-cap S&P 500 Index. In the first half of 2006, Columbia Acorn Fund rose 5.81%, slightly less than the Russell 2500 and somewhat more than the S&P 500.

Expeditors International of Washington, Columbia Acorn Fund's largest dollar winner in the first quarter, kept that distinction in the second quarter, delivering another 30% gain. Other winners included takeovers—12 Columbia Acorn stocks put themselves up for sale and announced deals in the quarter! Six takeovers wound up within the top dozen percentage performers for the quarter, including software firm RSA Security and Canadian mining company Falconbridge, each surging over 50%. Sweden's Gambro and Georgia-based Serologicals, both medical products companies, jumped a healthy 30% each. Aerospace components distributor Aviall and natural gas producer Western Gas Resources rounded out the takeover winner's circle, each rising nearly 25%.

Other big winners for the quarter included FMC Technologies, a manufacturer of deep-water oil and gas production systems, which reported earnings well ahead of expectations. So did World Acceptance, a consumer loan company, and both appreciated about 30%. Retailer Christopher & Banks improved its merchandise, regained its sales and earnings momentum, and marked up a 25% gain.

Columbia Acorn Fund's largest percentage losers were three biotech stocks, each giving back in the second quarter far more than they made in the first. DOV Pharmaceuticals reported that a test of a key drug was disappointing, and its stock collapsed 80%. Neurocrine Biosciences and Pozen both failed to get new drug approvals and each plunged about 66%. We sold all three. Retailer Chico's FAS suffered some merchandise misses, and its stock was discounted 34%. We bought more Chico's stock in the quarter, as we believed its problems are temporary.

The Fund's foreign stocks rose 3.14% in the quarter and 19.99% in the half year. Takeovers Falconbridge and Gambro, discussed above, helped drive results for the quarter. During the first half, oil-pipe makers Vallourec and Tenaris jumped 111% and 76%, respectively, while temporary staffing company USG People returned 82%. Swedish kitchen cabinet company Nobia racked up excellent growth, making a 25% gain in the quarter and a 62% return in the half. The Fund's worst performing international stock was Hong Kong's Techtronic Industries, down 43% in the half year.Columbia Acorn Fund's foreign stocks have performed spectacularly well since we decided to increase their weighting three years ago—up 174% vs. an 81% gain for the overall Fund.¹ We reviewed all of the Fund's foreign holdings during the period in an attempt to be more selective. We believe that many foreign stocks continue to appear cheaper than U.S. stocks, while others may not have enough upside to compensate for possible risks. Consequently, we cut the Fund's foreign stock weighting slightly, to 13.7%.

Charles P. McQuaid

Lead Portfolio Manager

Robert A. Mohn

Co-Portfolio Manager

¹By our calculations, Columbia Acorn Fund's foreign stocks had a total return of 173.71% in the three years ending June 2006. While we are extremely pleased with that return, we note that it is not comparable to mutual fund returns, as it is before expenses and cash effects incurred by actual funds. Also, Columbia Acorn Fund's foreign stockholdings have been heavily weighted toward energy and were not purchased as a balanced, stand-alone portfolio.

Small-cap stocks are often more volatile and less liquid than the stocks of larger companies. Small companies may have a shorter history of operations than larger companies and may have a less diversified product line, making them more susceptible to market pressure. Investments in foreign securities have special risks, including political or economic instability, higher costs, different regulations, accounting standards, trading practices and levels of information, and currency exchange rate fluctuations.

As of 6/30/06, the Fund's positions in the stocks mentioned were: Expeditors International of Washington, 1.7%; RSA Security, 0.4%; Falconbridge, 0.4%; Gambro, 0.0%; Serologicals, 0.3%; Aviall, 0.3%; Western Gas Resources, 1.1%; FMC Technologies, 0.9%; World Acceptance, 0.3%; Christopher & Banks, 0.6%; DOV Pharmaceuticals, 0.0%; Neurocrine Biosciences, 0.0%; Pozen, 0.0%; Chico's FAS, 0.9%; Vallourec, 0.2%; Tenaris, 0.3%; USG People, 0.3%; Nobia, 0.3%; Techtronic Industries, 0.1%.

1-800-922-6769

Columbia Acorn Fund

>At a Glance Ticker Symbol: ACRNX

Pretax and After-tax Average Annual Total Returns (Class Z)

>through June 30, 2006

Inception 6/10/70	Year to date*			1 year			5 years			10 years
Returns before taxes		5.81	%		16.44	%		12.31	%		14.97	%
Returns after taxes on distributions		5.64			15.48			11.92			13.13
Returns after taxes on distributions and sale of fund shares		4.00			11.90			10.72			12.39
Russell 2500 (pretax)		6.32			13.53			9.65			11.13
S&P 500 (pretax)		2.71			8.63			2.49			8.32

Performance shown here represents past performance, which does not guarantee future results. Current performance may be higher or lower. The investment return and principal value of an investment in the Fund will fluctuate so that Fund shares, when redeemed, may be worth more or less than their original cost. Visit columbiafunds.com for daily and most recent month-end updates.

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the additional tax impact of long-term gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class Z shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes.

*Year-to-date data not annualized.

Columbia Acorn Fund Portfolio Diversification

>as a % of net assets, as of June 30, 2006

The Growth of a $75,000 Investment in Columbia Acorn Fund (Class Z)

>June 10, 1970 through June 30, 2006

This graph compares the results of $75,000 invested in Columbia Acorn Fund at inception on June 10, 1970 to the S&P 500 Stock Index, a broad, market-weighted average of U.S. blue-chip company stock performance, and to an initial $238,325 investment in the Russell 2500, an index of the 2,500 smallest U.S. companies, on the index's December 31, 1978 inception date. The indexes are unmanaged and returns for both the indexes and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph and table do not reflect tax deductions that a shareholder would pay on Fund distributions or the sale of Fund shares.

NAV on 6/30/06: $29.49
Total Net Assets of the Fund: $17,916.1 million

*A $75,000 investment in Columbia Acorn Fund at inception appreciated to $238,325 on December 31, 1978, the inception date of the Russell 2500. For comparison with the Russell 2500, we assigned the index the same value as the Fund at index inception.

Columbia Acorn Fund Top 10 Holdings (as a % of net assets)

1. Expeditors International of Washington International Freight Forwarder	1.7	%
2. Coach Designer & Retailer of Branded Leather Accessories	1.2	%
3. Western Gas Resources Oil & Coal Seam Producer	1.1	%
4. AmeriCredit Auto Lending	1.0	%
5. Chico's FAS Women's Specialty Retail	0.9	%
6. Ultra Petroleum Natural Gas Producer	0.9	%
7. FMC Technologies Oil & Gas Well Head Manufacturer	0.9	%
8. Crown Castle International Communications Towers	0.9	%
9. ITT Educational Services Post-secondary Degree Programs	0.8	%
10. Peoples Bank Bridgeport Connecticut Savings & Loan	0.8	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

Columbia Acorn International

>In a Nutshell

Visit columbiafunds.com for daily and most recent month-end performance updates.

Columbia Acorn International ended the quarter down 1.11% vs. a 1.70% decline for the benchmark S&P/Citigroup EMI Global ex-US Index. Year-to-date through June 30, the Fund was up 14.27%, well ahead of the 10.57% gain of the index. The Fund's half year return also easily topped the 10.16% return of the large-cap oriented MSCI EAFE Index.

Energy stocks Tullow Oil and Fugro were among the top contributors to performance for both the quarter and the six months. Tullow Oil, an exploration and development company based in the United Kingdom, was up 21% in the quarter and 53% for the half year. Fugro, a Dutch provider of survey services to the offshore industry, posted a 14% return for the quarter and a 37% six-month gain. Both of these stocks are among the Fund's top 10 holdings.

European industrial stocks continued to perform well in the second quarter. Geberit, a Swiss manufacturer of pipes and fittings for plumbers, was up 23% in the quarter and 48% for the six months on improving demand in its key German market. RPS Group, a UK provider of environmental consulting services, gained 29% in the second quarter and was up over 50% for the half year. The stock benefited from strong growth in the energy sector and its other end markets. Sweden's Hexagon, a maker of measurement equipment and polymers, gained 9% in the quarter and was up 37% for the six months on strong trading in its metrology division and successful integration of Leica Geosystems, which it acquired last year.

In the health care sector, Sweden's Gambro, a manufacturer of dialysis and blood care products, gained more than 30% in the quarter and 45% for the half year before being acquired by Swedish investment companies Investor AB and EQT in June. Canadian mining company Falconbridge, up 51% in the quarter and over 78% for the half year, was a beneficiary of drawn out takeover action involving multiple suitors.

Underperformers in the quarter included African retailer Edgars Consolidated Stores, which fell 33% on concerns that rising interest rates may slow down consumption. In Japan, fund manager Sparx Asset Management fell 26% in sympathy with the overall correction in Japanese financial stocks. In Hong Kong, power tool manufacturer Techtronic Industries gave back 24% in the quarter. The stock was hurt by continued poor sentiment on the outlook for U.S. housing and its potential impact on power tool sales.

It is noteworthy that the Fund's slightly negative return for the second quarter masks much higher underlying volatility: The Fund began the quarter on a positive note rising 11.6% before hitting its peak on May 10 and then dropping 19% to reach a low on June 13. From that point, Fund performance recovered 9.4% to end the quarter down just slightly more than 1%. Concerns regarding ongoing increases in global interest rates seem to have conspired with historically high valuations to finally change investor appetite for international risk, particularly in international small-cap equities. Notably, the second quarter was also the first in 10 in which the large-cap EAFE index outperformed the small-cap EMI index. As in the U.S. market, overseas investors generally perceive larger cap stocks to be less risky than their small cap counterparts. As we have mentioned in earlier reports, small-cap international stocks have been strong performers in both absolute terms and relative to their large cap counterparts and no longer offer the valuation discount that they did before. While still finding compelling ideas in the sub US$5 billion market cap universe, we have been selectively adding mid-cap stocks in the US$5 to $10 billion range where valuations as a group are more attractive. Despite the increase in volatility in international small-cap equities, we believe there remain ample opportunities for new acorns to be discovered.

P. Zachary Egan

Co-Portfolio Manager

Louis J. Mendes III

Co-Portfolio Manager

Investments in foreign securities have special risk, including political or economic instability, higher costs, different regulations, accounting standards, trading practices and levels of information, and currency exchange rate fluctuations. Small-cap stocks are often more volatile and less liquid than the stocks of larger companies. Small companies may have a shorter history of operations than larger companies and may have a less diversified product line, making them more susceptible to market pressure.

As of 6/30/06, the Fund's positions in the stocks mentioned were: Tullow Oil, 1.3%; Fugro, 1.5%; Geberit, 1.0%; RPS Group, 0.8%; Hexagon, 1.6%; Gambro, 0.0%; Falconbridge, 0.5%; Edgars Consolidated Stores, 0.5%; Sparx Asset Management, 0.7%; Techtronic Industries, 0.5%.

1-800-922-6769

Columbia Acorn International

>At a Glance Ticker Symbol: ACINX

Pretax and After-tax Average Annual Total Returns (Class Z)

>through June 30, 2006

Inception 9/23/92	Year to date*			1 year			5 years			10 years
Returns before taxes		14.27	%		35.18	%		15.42	%		11.63	%
Returns after taxes on distributions		13.94			34.14			15.14			10.62
Returns after taxes on distributions and sale of fund shares		9.60			24.26			13.55			9.88
S&P/Citigroup EMI Global ex-US (pretax)		10.57			31.22			18.28			8.46

*Year-to-date data not annualized.

Columbia Acorn International Portfolio Diversification

>as a % of net assets, as of June 30, 2006

The Growth of a $10,000 Investment in Columbia Acorn International (Class Z)

>September 23, 1992 through June 30, 2006

This graph compares the results of $10,000 invested in Columbia Acorn International at inception on September 23, 1992 to the S&P/Citigroup EMI Global ex-US, Citigroup's index of the bottom 20% of institutionally investable capital of developed and emerging countries, as selected by Citigroup, excluding the U.S. The index is unmanaged and returns for both the index and Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph and table do not reflect tax deductions that a shareholder would pay on Fund distributions or the sale of Fund shares.

NAV as of 6/30/06: $37.58
Total Net Assets of the Fund: $3,596.3 million

Columbia Acorn International Top 10 Holdings (as a % of net assets)

1. Hexagon (Sweden) Measurement Equipment & Polymers	1.6	%
2. Fugro (Netherlands) Survey & GPS Services	1.5	%
3. USG People (Netherlands) Temporary Staffing Services	1.4	%
4. Tullow Oil (United Kingdom) Oil & Gas Producer	1.3	%
5. Aalberts Industries (Netherlands) Flow Control & Heat Treatment	1.1	%
6. Rhoen-Klinikum (Germany) Health Care Services	1.1	%
7. April Group (France) Insurance Policy Construction	1.0	%
8. Bank of Ireland (Ireland) Irish Commercial Bank	1.0	%
9. IAWS Group (Ireland) Baked Goods	1.0	%
10. Wincor Nixdorf (Germany) Retail POS Systems & ATM Machines	1.0	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

Columbia Acorn USA

>In a Nutshell

Visit columbiafunds.com for daily and most recent month-end performance updates.

After a first quarter surge, small caps pulled back in the second quarter. Columbia Acorn USA ended the second quarter down 4.39% vs. a 5.02% decline for the Russell 2000. First quarter underperformance dampened returns for the six-month period. Year-to-date through June 30, the Fund was up 2.19% vs. an 8.21% gain for the benchmark.

Six of our stocks received takeover offers during the quarter. Two of the six, Serologicals and Western Gas Resources, were fairly sizeable positions in the Fund and contributed positively to Fund returns as the stocks bounced on acquisition news. Serologicals, a producer of biological products and solutions, gained 29% in the quarter and was up over 59% for the six months. Western Gas Resources, a coal seam gas producer and processor, increased 24% in the second quarter and was up 27% year-to-date.

Other winners for the quarter and half year included FMC Technologies, up 32% in the quarter and 57% year-to-date. FMC makes deep-water oil and gas production systems and has been enjoying robust demand for its products as offshore drilling activity has increased. Crown Castle International, an owner of cellular communication towers, gained 22% in the quarter and 28% for the half year. Its business has been booming as cellular phone companies grab for more wireless capacity in order to beam internet sites, TV shows and other fun stuff to your cell phone.

While several Fund retail stocks faltered in the quarter, Christopher & Banks was the exception. Up 25% in the quarter and 55% for the six months, Christopher & Banks experienced a turnaround as new merchandise was positively received and same-store sales flipped from negative to positive. World Acceptance gained 30% in the quarter and was up 25% for the half year on news of strong loan growth in the second quarter and dramatically lower loan losses.

Interestingly enough, Neurocrine stock fell a further 50% after we got out. As mentioned, several retail names were down in the Fund. Oxford Industries, a maker of branded and private label apparel, fell 23% in the quarter and was off 28% for the six months on disappointing sales in its menswear lines. Chico's FAS, a women's specialty retailer, fell more than 34% in the quarter and 40% in the half year as new merchandise failed to move and sales came in short.

Two technology names, Avid Technology and CNET Networks also hurt Fund performance. Avid suffered indigestion from an acquisition it made last year and announced delays in new product upgrades. The stock was off 23% in the quarter and 38% for the six months. CNET Networks, a provider of software product reviews and niche technology websites, was off 44% in the quarter and 46% for the half year. CNET's business is driven by new product launches, and two highly anticipated product launches, Microsoft's Vista and Sony's PlayStation 3, were tardy.

The second quarter's pull back in small-cap stocks allowed us to add to positions in fast-growing stocks whose prices had fallen within our valuation criteria. We continue to take advantage of the many opportunities that we believe today's volatile markets offer.

Robert A. Mohn

Lead Portfolio Manager

As of 6/30/06, the Fund's positions in the stocks mentioned were: Serologicals, 1.2%; Western Gas Resources, 1.2%; FMC Technologies, 1.8%; Crown Castle International, 2.4%; Christopher & Banks, 1.0%: World Acceptance, 1.3%; Neurocrine Biosciences, 0.0%; Oxford Industries, 1.7%; Chico's FAS, 0.6%; Avid Technology, 1.8%; CNET Networks, 0.5%.

1-800-922-6769

Columbia Acorn USA

>At a Glance Ticker Symbol: AUSAX

Pretax and After-tax Average Annual Total Returns (Class Z)

>through June 30, 2006

Inception 9/4/96	Year to date*			1 year			5 years			Life of fund
Returns before taxes		2.19	%		9.45	%		9.58	%		14.04	%
Returns after taxes on distributions		2.13			8.78			9.29			13.34
Returns after taxes on distributions and sale of fund shares		1.50			7.02			8.28			12.30
Russell 2000 (pretax)		8.21			14.58			8.50			9.63

*Year-to-date data not annualized.

Columbia Acorn USA Portfolio Diversification

>as a % of net assets, as of June 30, 2006

The Growth of a $75,000 Investment in Columbia Acorn USA (Class Z)

>September 4, 1996 through June 30, 2006

This graph compares the results of $75,000 invested in Columbia Acorn USA at inception on September 4, 1996 to the Russell 2000 Index, a market-weighted index of 2,000 smaller U.S. companies formed by taking the largest 3,000 U.S. companies and eliminating the largest 1,000. The index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph and table do not reflect tax deductions that a shareholder would pay on Fund distributions or the sale of Fund shares.

NAV as of 6/30/06: $27.52
Total Net Assets of the Fund: $1,470.3 million

Columbia Acorn USA Top 10 Holdings (as a % of net assets)

1. Crown Castle International Communication Towers	2.4	%
2. AmeriCredit Auto Lending	2.1	%
3. Esco Technologies Automatic Electric Meter Readers	2.1	%
4. ITT Educational Services Post-secondary Degree Programs	1.9	%
5. Genlyte Group Commercial Lighting Fixtures	1.9	%
6. FMC Technologies Oil & Gas Well Head Manufacturer	1.8	%
7. Edwards Lifesciences Heart Valves	1.8	%
8. Avid Technology Digital Nonlinear Editing Software & Systems	1.8	%
9. Oxford Industries Branded & Private Label Apparel	1.7	%
10. Kronos Labor Management Solutions	1.6	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

Columbia Acorn International Select

>In a Nutshell

Visit columbiafunds.com for daily and most recent month-end performance updates.

Columbia Acorn International Select ended the second quarter up 0.48%, outperforming the 0.61% drop of S&P/Citigroup World ex-US Cap Range $2-10B Index. Year-to-date through June 30, the Fund was up 12.83%, well ahead of the 10.29% return of the index.

Strong contributors to performance in the quarter and half year included Sweden's Gambro, a producer of renal and blood care products, and one of the Fund's largest holdings. The stock increased 44% in 2006 before it was acquired by Swedish investment companies Investor AB and EQT in June. Hong Kong Exchanges and Clearing, the Hong Kong equities and derivatives operator and another of the Fund's major holdings, was up 57% for the semiannual period, gaining 8% in the second quarter as it continued to benefit from growing trading volumes and new stock listings from China. Geberit, a Swiss manufacturer of plumbing supplies, gained 48% in the first half of the year and 23% in the second quarter thanks to improving demand in its key German market. C&C Group, an Irish beverage and snack company, was added to the Fund in the first quarter and was among its top five contributors for the quarter and half year. The company continues to make significant inroads into the UK alcoholic beverage market with its hard cider offering that is so popular in Ireland.

Most laggards for the quarter and six months had one thing in common: Japan. After a strong rally in the fourth quarter of 2005 in Japan, corporate governance issues at a few small firms roiled the local markets and contributed to a general sell-off. In the quarter, fund manager Sparx Asset Management fell 28% despite significant earnings upgrades and increases in assets under management. Kansai Paint, a paint producer based in Japan but with operations throughout emerging Asia, fell 13%. Aeon Mall, a suburban shopping mall developer and operator, fell 16%. For the six months, Jupiter Telecommunications, the largest cable service provider in Japan, was off 13%. Outside of Japan, France's SES Global, a provider of satellite broadcasting services, fell 17% in the first half of 2006 due to higher than expected start-up costs for new activities.

While increasing interest rates, higher oil prices and geopolitical concerns have all contributed to rising volatility in the equity markets, earnings for companies in Columbia Acorn International Select's portfolio have generally come in as expected or on the higher side of expectations. As a result, we are seeing more value emerging due to the recent drop in the market. However, things can quickly change and we will continue to monitor the fundamental outlook for Fund holdings closely.

Christopher J. Olson

Lead Portfolio Manager

Mid-cap stocks tend to be more volatile and may be less liquid than the stocks of larger companies. Investments in foreign securities have special risk, including political or economic instability, higher costs, different regulations, accounting standards, trading practices and levels of information, and currency exchange rate fluctuations.

As of 6/30/06, the Fund's positions in the stocks mentioned were: Gambro, 0.0%; Hong Kong Exchanges and Clearing, 3.3%; Geberit, 2.3%; C&C Group, 3.6%; Sparx Asset Management, 1.6%; Kansai Paint, 1.9%; Aeon Mall, 1.9%; Jupiter Telecommunications, 3.1%; SES Global, 2.2%.

1-800-922-6769

Columbia Acorn International Select

>At a Glance Ticker Symbol: ACFFX

Pretax and After-tax Average Annual Total Returns (Class Z)

>through June 30, 2006

Inception 11/23/98	Year to date*			1 year			5 years			Life of fund
Returns before taxes		12.83	%		30.10	%		11.83	%		12.25	%
Returns after taxes on distributions		12.75			30.15			11.83			12.17
Returns after taxes on distributions and sale of fund shares		8.34			19.70			10.41			10.89
S&P/Citigroup World ex-US Cap Range $2-10B (pretax)		10.29			31.69			15.80			11.52

*Year-to-date data not annualized.

Columbia Acorn International Select Portfolio Diversification

>as a % of net assets, as of June 30, 2006

The Growth of a $10,000 Investment in Columbia Acorn International Select (Class Z)

>November 23, 1998 through June 30, 2006

This graph compares the results of $10,000 invested in Columbia Acorn International Select at inception on November 23, 1998 to the S&P/Citigroup World ex-US Cap Range $2-10B Index, a subset of Citigroup's Broad Market Index, representing a mid-cap developed market index excluding the U.S. The index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph and table do not reflect tax deductions that a shareholder would pay on Fund distributions or the sale of Fund shares.

NAV on 6/30/06: $23.16
Total Net Assets of the Fund: $119.2 million

Columbia Acorn International Select Top 10 Holdings (as a % of net assets)

1. Bank of Ireland (Ireland) Irish Commercial Bank	4.2	%
2. C&C Group (Ireland) Beverage Company	3.6	%
3. Daito Trust Construction (Japan) Apartment Builder	3.5	%
4. Anglo Irish Bank (Ireland) Small Business & Middle Market Banking	3.5	%
5. Northern Rock (United Kingdom) Lowest Cost Mortgage Bank in UK	3.3	%
6. Hoya (Japan) Opto-Electrical Components & Eyeglass Lenses	3.3	%
7. Hong Kong Exchanges and Clearing (Hong Kong) Hong Kong Equity & Derivatives Market Operator	3.3	%
8. IAWS Group (Ireland) Baked Goods	3.3	%
9. Jupiter Telecommunications (Japan) Largest Cable Service Provider in Japan	3.1	%
10. Synthes (Switzerland) Products for Orthopedic Surgery	3.0	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

Columbia Acorn Select

>In a Nutshell

Visit columbiafunds.com for daily and most recent month-end performance updates.

Columbia Acorn Select was down 2.22% in the second quarter vs. a 3.14% decline of the S&P MidCap 400 Index. Year-to-date through June 30, the Fund was up 5.43%, 1.19% greater than its S&P MidCap 400 benchmark and 2.72% greater than the S&P 500's year-to-date gain of 2.71%.

Focusing on the stocks that drove Columbia Acorn Select's performance for the quarter and six months, the Fund had one stock that was consistently up and one stock that was consistently down for the half year. The Fund's up stock was Expeditors International of Washington, a freight forwarding company. Expeditors gained more than 60% for the semiannual period and added 1.6% to the Fund's overall portfolio return. On the negative side, Avid Technology cost the Fund approximately 1.6% of overall performance year-to-date. As mentioned last quarter, Avid's acquisition of Pinnacle did not initially meet expectations. I recently met with Avid's divisional head of Pinnacle, and I also met with an Avid customer. Though it's clear that we put Avid into the Fund too early, our confidence has consistently grown as well as the Fund's share position. We believe Avid is putting the right management and products in place to build on its leading market share in consumer video, broadcast, storage and audio.

Tellabs also hindered performance in the second quarter as the telecom sector seemed to fall out of favor with investors. We still believe Tellabs' strong fundamentals should help the company outperform over the next couple of years.

The Fund sold out of four existing positions in the quarter and purchased one new position. Three of the sales were made because we believed company fundamentals were beginning to weaken (Coventry Health Care, Associated Banc-Corp and Tektronix). IAC/Interactive, a smaller position in the Fund, was sold because we felt it was expensive. The new addition was Sanmina-SCI, a provider of electronics contract manufacturing services (EMS). Columbia Wanger Asset Management owned and sold Sanmina pre-2000 before the EMS industry got overheated. Numerous EMS companies purchased manufacturing assets or other EMS players at ridiculously high prices during the Internet bubble. Sanmina was no exception during this phase; it purchased several companies in 2000 and 2001. Since the acquisitions, Sanmina has struggled to improve its operating margins, but we believe the company is now on track to improve its bottom line.

U.S. stocks began to decline in the weeks following the period end. The main fear is that rising global interest rates could curtail economic growth. The small-cap Russell 2000 Index, which had been up more than 16% early in the second quarter, lost almost all of this gain just following the period end in mid-July. We noted at the end of the third quarter last year that smaller cap stocks were somewhat expensive compared to their larger cap peers. At that point, we were finding better value in larger mid-cap names. In the first few months of this year small caps got even more expensive before taking the mid-year dive. This recent sell-off has corrected some of the excess, and we are now finding some interesting stock ideas to watch among the smaller end of the Fund's investment range. We're not ready to load up on these ideas yet, but we believe that they have a lot of promise and could be drivers of the Fund's portfolio next year. Could the economy slow down in the next few quarters and make some of these ideas less promising? Sure. But it's been our experience that the market usually overreacts to a slowing economy, making new investment ideas more attractive.

Ben Andrews

Lead Portfolio Manager

Columbia Acorn Select is a non-diversified fund. The performance of each of its holdings will have a greater impact on the Fund's total return, and may make the Fund's returns more volatile than a more diversified fund. Mid-cap stocks tend to be more volatile and may be less liquid than the stocks of larger companies.

As of 6/30/06, the Fund's positions in the stocks mentioned were: Expeditors International of Washington; 3.8%; Avid Technology, 2.8%; Tellabs, 6.7%; Coventry Health Care, 0.0%; Associated Banc-Corp, 0.0%; Tektronix, 0.0%; IAC/Interactive, 0.0%; Sanmina-SCI, 0.9%.

1-800-922-6769

Columbia Acorn Select

>At a Glance Ticker Symbol: ACTWX

Pretax and After-tax Average Annual Total Returns (Class Z)

>through June 30, 2006

Inception 11/23/98	Year to date*			1 year			5 years			Life of fund
Returns before taxes		5.43	%		17.28	%		11.75	%		14.46	%
Returns after taxes on distributions		5.22			16.63			11.50			13.94
Returns after taxes on distributions and sale of fund shares		3.53			11.75			10.22			12.66
S&P MidCap 400 (pretax)		4.24			12.98			9.30			11.95

*Year-to-date data not annualized.

Columbia Acorn Select Portfolio Diversification

>as a % of net assets, as of June 30, 2006

The Growth of a $50,000 Investment in Columbia Acorn Select (Class Z)

>November 23, 1998 through June 30, 2006

This graph compares the results of $50,000 invested in Columbia Acorn Select at inception on November 23, 1998 to the S&P MidCap 400, a broad, market-weighted index of 400 stocks that are in the next size/tier down from the S&P 500. The index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph and table do not reflect tax deductions that a shareholder would pay on Fund distributions or the sale of Fund shares.

NAV on 6/30/06: $23.87
Total Net Assets of the Fund: $1,937.7 million

Columbia Acorn Select Top 10 Holdings (as a % of net assets)

1. Tellabs Telecommunications Equipment	6.7	%
2. ITT Educational Services Post-secondary Degree Programs	5.5	%
3. Liberty Global CATV Holding Company	4.7	%
4. Safeway Supermarkets	4.7	%
5. UrAsia Energy (Canada) Uranium Mining in Kazakhstan	4.1	%
6. Abercrombie & Fitch Teen Apparel Retailer	4.0	%
7. Expeditors International of Washington International Freight Forwarder	3.8	%
8. American Tower Communication Towers in USA & Mexico	3.7	%
9. Pride International Contract Drilling	3.1	%
10. Harley-Davidson Motorcycles & Related Merchandise	3.1	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

Columbia Thermostat Fund

>In a Nutshell

Visit columbiafunds.com for daily and most recent month-end performance updates.

A "fund of funds" bears its allocable share of the costs and expenses of the underlying funds in which it invests. Such funds are thus subject to two levels of fees and potentially higher expense ratio than would be associated with an investment in an investment fund that invests and trades directly in financial instruments under the direction of a single manager.

Columbia Thermostat Fund ended the second quarter down 0.55%. This compares to a 1.44% decline for the S&P 500 and a 0.06% gain for the Lehman Brothers U.S. Credit Intermediate Bond Index. The Lipper Flexible Portfolio Funds Index fell 1.30% for the three-month period. For the half year, the Fund was up 2.56% vs. 2.71% for the S&P 500, a 0.47% decline for the Lehman Brothers U.S. Credit Intermediate Bond Index and a 3.07% gain for the Lipper Flexible Portfolio Funds Index.

While the bond portion of the portfolio held up slightly better in the second quarter, both stocks and bonds were slightly negative as the markets dropped modestly. The first quarter's equity surge helped the stock portion of the portfolio maintain a gain of 5.79% for the six-month period. The bond portion was down 0.78% for the six months.

The Fund hit two reallocation triggers in the second quarter. In April the stock component was raised 5% to 45% of the portfolio. In June the weighting was raised again to 50% stocks, 50% bonds.

So far 2006 has been the type of investment environment for which Columbia Thermostat Fund was made. Thank you for your investment in the Fund.

Charles P. McQuaid

Lead Portfolio Manager

Results of the Funds Owned in Columbia Thermostat Fund at June 30, 2006

Equities

Fund	Weightings in Category			2nd quarter returns			6-month returns to 6/30/06
Columbia Acorn Fund		15	%		-3.73	%		5.81	%
Columbia Acorn Select		10	%		-2.22	%		5.43	%
Columbia Large Cap Value Fund		15	%		-0.57	%		5.45	%
Columbia Acorn International		15	%		-1.11	%		14.27	%
Columbia Dividend Income Fund		20	%		0.48	%		4.07	%
Columbia Large Cap Enhanced Core Fund		25	%		-2.15	%		2.40	%
*Weighted Average* *Equity Return*		*100*	%		*-1.45*	%		*5.79*	%

Fixed Income

Fund	Weightings in Category			2nd quarter returns			6-month return to 6/30/06
Columbia Federal Securities Fund		30	%		-0.26	%		-1.13	%
Columbia Intermediate Bond Fund		50	%		-0.22	%		-0.71	%
Columbia Conservative High Yield Fund		20	%		-1.70	%		-0.42	%
*Weighted Average* *Income Return*		*100*	%		*-0.53*	%		*-0.78*	%

Columbia Thermostat Fund Rebalancing in the Second Quarter

April 17, 2006:				45% stock, 55% bond
June 13, 2006:				50% stock, 50% bond

The value of an investment in the Fund is based primarily on the performance of the underlying portfolio funds and the allocation of the Fund's assets among them. An investment in the underlying funds may present certain risks, including stock market fluctuations that occur in response to economic and business developments; and a greater degree of social, political and economic volatility associated with international investing. Investing in small- and mid-cap stocks may present special risks including possible illiquidity and greater price volatility than stocks of larger, more established companies. Investments in foreign securities have special risks including political or economic instability, higher costs, different regulations, accounting standards, trading practices and levels of information, and currency exchange rate fluctuations. Changes in interest rates and changes in the financial strength of issuers of lower-rated bonds may also affect underlying fund performance. The Fund is also subject to the risk that the investment adviser's decisions regarding asset classes and portfolio funds will not anticipate market trends successfully, resulting in a failure to preserve capital or lower total return. In addition, the Fund may buy and sell shares of the portfolio funds frequently. This may result in higher transaction costs and additional tax liability. This is not an offer of the shares of any other mutual fund mentioned herein.

1-800-922-6769

Columbia Thermostat Fund

>At a Glance Ticker Symbol: COTZX

Pretax and After-tax Average Annual Total Returns (Class Z)

>through June 30, 2006

Inception 9/25/02	Year to date*			1 year			3 year			Life of fund
Returns before taxes		2.56	%		6.65	%		9.08	%		10.83	%
Returns after taxes on distributions		2.13			4.35			7.70			9.71
Returns after taxes on distributions and sale of fund shares		2.04			5.77			7.25			8.93
S&P 500 (pretax)		2.71			8.63			11.22			14.41
Lehman Brothers U.S. Credit Intermediate Bond Index (pretax)		-0.47			-0.61			1.83			3.97
Lipper Flexible Portfolio Funds Index (pretax)		3.07			10.01			10.40			12.58

Investment returns and principal value may fluctuate, resulting in a gain or loss on sale.

*Year-to-date data not annualized.

Columbia Thermostat Fund Portfolio Weightings

>as a % of assets in each investment category, as of June 30, 2006

The Growth of a $10,000 Investment in Columbia Thermostat Fund (Class Z)

>September 25, 2002 through June 30, 2006

This graph compares the results of $10,000 invested in Columbia Thermostat Fund at inception on September 25, 2002 to three indexes. The S&P 500 is a broad, market-weighted average of U.S. blue-chip company stock performance. The Lehman Brothers U.S. Credit Intermediate Bond Index is the intermediate component of the U.S. Credit Index. The U.S. Credit Index includes publicly issued U.S. corporate and foreign debentures and secured notes that meet specified maturity, liquidity, and quality requirements. The Lipper Flexible Portfolio Funds Index is an equal dollar weighted index of the 30 largest mutual funds within the Flexible Portfolio Fund classification, as defined by Lipper. The indexes are unmanaged and returns for the indexes and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index. The graph and table do not reflect tax deductions that a shareholder would pay on Fund distributions or the sale of Fund shares.

NAV on 6/30/06: $12.53
Total Net Assets of the Fund: $191.3 million

Columbia Thermostat Fund Asset Allocation

>as a % of net assets, as of June 30, 2006

Columbia Acorn Fund

>Major Portfolio Changes in the Second Quarter (Unaudited)

	Number of Shares
	03/31/06		06/30/06
Additions
Information
Alliance Atlantis Communication (Canada)		960,000		1,423,100
Amphenol		1,540,000		1,620,000
Avnet		2,300,000		2,550,000
Belden CDT		1,173,000		1,705,000
Ceridian		2,435,000		2,585,000
CNET Networks		3,000,000		4,000,000
Concur Technologies		675,000		1,766,000
EResearch Technology		0		1,050,000
Gemstar-TV Guide International		7,912,000		8,000,000
II VI		1,635,000		1,885,000
Integrated Device Technology		3,060,000		3,390,000
Kenexa		0		160,000
Kronos		2,250,000		2,750,000
Micros Systems		1,425,000		1,800,000
Navigant Consulting		1,836,000		1,900,000
Nice Systems (Israel)		1,434,000		1,634,000
(includes the effect of a 2 for 1 stock split)
Novell		11,500,000		12,000,000
Openwave Systems		0		1,500,000
Proquest Company		0		2,000,000
Radiant Systems		0		1,100,000
Saga Communications		924,000		1,400,000
Sanmina - SCI		0		4,000,000
Supertex		565,000		690,000
Symbol Technologies		2,560,000		4,425,000
Tellabs		9,800,000		10,000,000
THQ		1,050,000		1,700,000
Tumbleweed Communications		1,761,000		3,240,000
ValueClick		2,000,000		3,000,000
webMethods		518,000		1,240,000
Consumer Goods/Services
Abercrombie & Fitch		2,000,000		2,200,000
Borders Group		1,300,000		1,450,000
C&C Group (Ireland)		0		2,500,000
Cavco Industries		55,000		172,000
Champion Enterprises		0		900,000
Chattem		0		750,000
Chico's FAS		5,090,000		5,960,000
Coach		5,980,000		6,980,000
Ducati Motor (Italy)		2,850,000		5,700,000
Expedia		0		3,500,000
Fleetwood Enterprises		4,190,000		4,690,000
Helen of Troy		1,416,000		1,800,000
HNI		2,400,000		2,550,000
Jarden		800,000		1,000,000
J Crew Group		0		1,100,000
Localiza Rent A Car		0		168,800
Pool Corporation		1,820,000		2,190,000
Princeton Review		1,939,000		2,550,000

	Number of Shares
	03/31/06		06/30/06
Consumer Goods/Services—continued
Red Robin Gourmet Burgers		805,000		1,000,000
Rite Aid		7,850,000		8,000,000
Scotts Miracle-Gro		1,790,000		2,620,000
ServiceMaster		0		470,000
Station Casinos		885,000		1,000,000
Thor Industries		201,000		441,000
True Religion Apparel		600,000		700,000
Universal Technical Institute		100,000		1,000,000
Urban Outfitters		2,427,000		3,900,000
Industrial Goods/Services
Donaldson		3,275,000		3,600,000
Drew Industries		730,000		1,048,000
Flir Systems		1,300,000		1,850,000
Florida Rock Industries		1,537,000		1,900,000
Goodman Global		0		1,600,000
K&F Industries Holdings		994,000		1,187,000
Legrand (France)		0		700,000
Martin Marietta		0		605,000
Quanta Services		2,481,000		2,500,000
Simpson Manufacturing		1,450,000		2,200,000
UTI Worldwide		2,700,000		3,000,000
Worthington Industries		1,964,000		2,160,000
W.W. Grainger		0		750,000
Finance
AmeriCredit		6,321,000		6,500,000
Assurant		830,000		1,200,000
Cascade Bancorp		118,000		500,000
Chittenden		756,000		892,000
Delphi Financial Group		250,000		750,000
(includes the effect of a 3 for 2 stock split)
East West Bancorp		0		400,000
Eaton Vance		3,170,000		3,970,000
Electro Rent		361,000		832,000
Great Southern Bancorp		675,000		796,000
Greene County Bancshares		0		150,000
Marlin Business Services		0		263,000
McGrath Rentcorp		550,000		930,000
National Financial		0		600,000
Philadelphia Consolidated Holding		1,725,000		2,040,000
Scottish Re Group		0		1,700,000
West Bancorporation		758,000		886,000
Energy/Minerals
Atwood Oceanics		0		1,000,000
Fugro (Netherlands)		1,235,000		2,728,302
Helmerich & Payne		0		257,000
Hugoton Royalty		0		150,000
Maritrans		0		600,000
Rowan		0		971,000

1-800-922-6769

	Number of Shares
	03/31/06		06/30/06
Additions (continued)
Health Care
LCA Vision		621,000		875,000
Rigel Pharmaceuticals		1,216,000		1,275,000
Tercica		198,000		1,500,000
Other Industries
Gaylord Entertainment		1,400,000		1,560,000
Highland Hospitality		4,825,000		5,850,000
Parkway Properties		400,000		536,000
Sales
Information
Activision		2,000,000		1,000,000
Andrew		1,750,000		1,380,000
CDW		295,000		0
Getty Images		1,200,000		600,000
Hong Kong Exchanges and Clearing (Hong Kong)		9,000,000		6,500,000
International Game Technology		3,840,000		2,750,000
Jabil Circuit		2,275,000		1,705,000
Logitech (Switzerland)		300,000		0
MRO Software		1,000,000		241,000
Novatek Microelectronics (Taiwan)		5,254,000		4,000,000
Plexus		1,961,000		1,570,000
RSA Security		3,000,000		2,500,000
Sybase		1,000,000		0
Consumer Goods/Services
Aeropostale		1,040,000		936,000
Coinstar		1,440,000		0
Columbia Sportswear		400,000		0
IAWS Group (Ireland)		1,900,000		1,597,000
Intrawest (Canada)		1,044,000		900,000
Michaels Stores		3,560,000		2,760,000
Natura Cosmeticos		3,150,000		1,100,000
Park 24 (Japan)		870,000		154,000
Shimano (Japan)		780,000		90,000
Sports Authority		1,520,000		0
Zale		1,072,000		0
Industrial Goods/Services
Administaff		1,300,000		1,100,000
Grafton Group (Ireland)		3,800,000		3,500,000
Kingspan Group (Ireland)		1,250,000		1,000,000
Spartech		3,150,000		2,800,000
Tenaris (Argentina)		1,800,000		1,500,000
(includes the effect of a 5 for 1 stock split)
Tennant		150,000		0
Ultrapar (Brazil)		750,000		438,000
USG People (Netherlands)		740,000		650,000
Vallourec (France)		95,200		33,000
Wienerberger (Austria)		425,000		0

	Number of Shares
	03/31/06		06/30/06
Finance
Anglo Irish Bank (Ireland)		3,600,000		3,500,000
Bankinter (Spain)		200,000		0
Cascade Financial		477,500		0
(includes the effect of a 5 for 4 stock split)
Independent Bank		265,000		0
Investment Technology Group		690,000		350,000
Leucadia National		1,993,000		1,748,000
(includes the effect of a 2 for 1 stock split)
Northgate (United Kingdom)		1,000,000		0
Paragon Group (United Kingdom)		1,950,000		1,120,000
Republic		1,581,000		0
Scottish Re Group		1,700,000		0
Sterling Bancorp		503,000		0
TCF Financial		3,356,000		3,156,000
Energy/Minerals
Chicago Bridge & Iron		1,600,000		1,193,000
Newpark Resources		5,000,000		2,860,000
Pioneer Drilling		168,000		0
Saipem (Italy)		2,000,000		1,200,000
Sociedad Quimica Y Minera de Chile (Chile)		275,000		195,000
Talisman Energy (Canada)		7,500,000		4,900,000
(includes the effect of a 2 for 1 stock split)
Veritas DGC		700,000		350,000
Health Care
Charles River Laboratories		1,595,000		1,355,000
Datascope		1,065,000		455,000
DOV Pharmaceuticals		1,540,000		0
Gambro (Sweden)		4,260,000		0
Incyte		3,935,000		0
Martek Biosciences		650,000		0
Neurocrine Biosciences		913,000		0
Pozen		2,400,000		0
Sybron Dental Specialties		283,000		0
Symmetry Medical		965,000		0
Tanox		685,000		0
United Drug (Ireland)		4,145,810		4,000,000
Other Industries
Comfort Del Gro (Singapore)		18,000,000		0
Grupo Aeroportuario Del Sureste (Mexico)		800,000		760,000
Heartland Express		1,634,000		1,584,000
(includes the effect of a 4 for 3 stock split)

Columbia Acorn Fund

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares			Value (000)
			Common Stocks and Other Equity-Like Securities: 93.8%
Information: 22.8%
		Software/Services
		>Business Software: 3.3%
	2,750,000	Kronos (b)(c)	$	99,577
		Labor Management Solutions
	12,000,000	Novell (b)		79,560
		Directory, Operating System & Identity Management Software
	1,800,000	Micros Systems (b)		78,624
		Information Systems for Restaurants & Hotels
	1,800,000	Avid Technology (b)		59,994
		Digital Nonlinear Editing Software & Systems
	1,800,000	Cadence Design Systems (b)		30,870
		Electronic Design Automation
	1,427,000	Witness Systems (b)		28,783
		Customer Experience Management Software
	1,766,000	Concur Technologies (b)		27,320
		Web Enabled Enterprise Applications
	6,000,000	Actuate (b)(c)		24,240
		Information Delivery Software & Solutions
	1,000,000	Progress Software (b)		23,410
		Application Development Software
	1,490,000	JDA Software (b)(c)		20,905
		Applications/Software & Services for Retailers
	3,000,000	Lawson Software (b)		20,100
		Enterprise Resource Planning (ERP) Software
	928,000	SSA Global Technologies (b)		17,985
		Enterprise Resource Planning (ERP) Software
	5,600,000	Indus International (b)(c)		16,016
		Enterprise Asset Management Software
	1,200,000	Parametric Technology (b)		15,252
		Engineering Software & Services
	2,075,000	Agile Software (b)		13,156
		Product Design Software
	1,240,000	webMethods (b)		12,239
		Enterprise Applications Integration (EAI) Tools
	1,100,000	Radiant Systems (b)		11,627
		Point of Sale System: Convenient Stores & Restaurants
	3,240,000	Tumbleweed Communications (b)(c)		9,234
		Email Content Security & File Transfer Management
	160,000	Kenexa (b)		5,096
		Human Capital Management Software
	241,000	MRO Software (b)		4,837
		Enterprise Maintenance Software
	1,250,000	ClickSoftware Technologies (b)		2,150
		Service Chain Optimization Software
				600,975
		>Business Information/ Business Services/Publishing: 1.5%
	2,585,000	Ceridian (b)		63,177
		HR Services & Payment Processing
	1,900,000	Navigant Consulting (b)		43,035
		Financial Consulting Firm
	600,000	Getty Images (b)		38,106
		Photographs for Publications & Electronic Media
	916,000	Fair Isaac		33,260
		Credit Scoring & Decision Analytic Software

Number of Shares			Value (000)
	2,000,000	Proquest Company (b)(c)	$	24,580
		Information Services for Educational & Automotive Services
	2,285,000	InfoUSA		23,558
		Business Data for Sales Leads
	1,500,000	Openwave Systems (b)		17,310
		Internet Software for Mobile Devices
	300,000	Navteq (b)		13,404
		Map Data for Electronic Devices
	2,500,000	PRIMEDIA (b)		4,575
		Specialty Magazines & Other Publications
	175,000	Triple Crown Media (b)		1,517
		Newspapers, Paging & Collegiate Sports Marketing
				262,522
		>Internet: 1.2%
	2,500,000	RSA Security (b)		67,975
		Enterprise Security Software
	9,500,000	Skillsoft Publishing (b)(c)		58,140
		Provider of Web-Based Learning Solutions (E-Learning)
	3,000,000	ValueClick (b)		46,050
		Internet Advertising
	4,000,000	CNET Networks (b)		31,920
		Internet Advertising on Niche Websites
	875,000	Vital Stream (b)		9,275
		Streaming Services for the Internet
	61,000	Travelzoo (b)		1,851
		Travel Internet Advertising
				215,211
		>Transaction Processors: 1.0%
	2,524,000	Global Payments		122,540
		Credit Card Processor
	6,500,000	Hong Kong Exchanges and Clearing (Hong Kong)		41,776
		Hong Kong Equity & Derivatives Market Operator
	600,000	Cubic		11,766
		Revenue Collection & Defense Systems
				176,082
		>Computer Services: 0.7%
	1,350,000	SRA International (b)		35,951
		Government I/T Services
	4,000,000	Bearing Point (b)		33,480
		Business Consulting & Technology Strategy
	5,000,000	Igate Capital (b)(c)		31,950
		I/T & BPO Outsourcing Services
	4,600,000	AnswerThink Consulting (b)(c)		18,538
		I/T Integration & Best Practice Research
				119,919
		>Electronics Distribution: 0.5%
	2,550,000	Avnet (b)		51,051
		Electronic Components Distribution
	680,000	Tech Data (b)		26,051
		I/T Distributor
	710,000	Agilysys		12,780
		I/T Distributor
				89,882

1-800-922-6769

Number of Shares			Value (000)
		>Consumer Software: 0.3%
	1,700,000	THQ (b)	$	36,720
		Entertainment Software
	1,000,000	Activision (b)		11,380
		Entertainment Software
				48,100
		Computer Related Hardware
		>Computer Hardware/ Related Systems: 3.3%
	1,620,000	Amphenol		90,655
		Electronic Connectors
	1,705,000	Belden CDT		56,350
		Specialty Cable
	870,000	Rogers (b)		49,016
		PCB Laminates & High Performance Foams
	4,425,000	Symbol Technologies		47,746
		Mobile Computers & Barcode Scanners
	1,634,000	Nice Systems (Israel) (b)		45,981
		Audio & Video Recording Solutions
	1,885,000	II VI (b)(c)		34,496
		Laser Components
	230,000	Wincor Nixdorf (Germany)		29,367
		Retail POS Systems & ATM Machines
	253,600	Neopost (France)		28,869
		Postage Meter Machines
	1,240,000	Intermec (b)		28,446
		Bar Code & Wireless LAN Systems
	9,761,000	Advantech (Taiwan)		28,019
		Embedded Computers
	1,027,000	Avocent (b)		26,959
		Computer Control Switches
	1,310,000	CTS		19,506
		Electronic Components, Sensors & EMS
	900,000	Netgear (b)		19,485
		Networking Products for Small Business & Home
	625,000	Excel Technologies (b)(c)		18,700
		Laser Systems & Electro-Optical Components
	530,000	Zebra Technologies (b)		18,105
		Bar Code Printers
	375,000	Diebold		15,233
		Automated Teller Machines
	1,875,000	Seachange International (b)(c)		13,050
		Systems for Video on Demand & Ad Insertion
	5,000,000	Concurrent Computer (b)(c)		13,050
		Video on Demand Systems & Services
	11,999,000	Phoenixtec Power (Taiwan)		12,196
		Uninterruptible Power Supplies
				595,229
		>Gaming Equipment: 1.4%
	2,750,000	International Game Technology		104,336
		Slot Machines & Progressive Jackpots
	2,430,000	Shuffle Master (b)(c)		79,655
		Card Shufflers & Casino Games
	3,900,000	Bally Technologies (b)(c)		64,233
		Slot Machines & Software
				248,224

Number of Shares			Value (000)
		>Semiconductors/ Related Equipment: 1.3%
	3,390,000	Integrated Device Technology (b)	$	48,070
		Communications Semiconductors
	4,425,000	Entegris (b)		42,170
		Semiconductor Wafer Shipping & Handling Products
	915,000	Littelfuse (b)		31,458
		Little Fuses
	690,000	Supertex (b)(c)		27,559
		Mixed-Signal Semiconductors
	1,950,000	AMIS Holdings (b)		19,500
		Analog & Mixed - Signal Semiconductors
	4,000,000	Novatek Microelectronics (Taiwan)		19,268
		LCD Related IC Designer
	1,905,000	IXYS (b)(c)		18,288
		Power Semiconductors
	1,235,000	Semtech (b)		17,846
		Analog Semiconductors
				224,159
		>Instrumentation: 1.2%
	1,250,000	Trimble Navigation (b)		55,800
		GPS-Based Instruments
	750,000	Mettler Toledo (b)		45,428
		Laboratory Equipment
	1,850,000	Flir Systems (b)		40,811
		Infrared Cameras
	711,000	Dionex (b)		38,863
		Ion & Liquid Chromatography
	670,000	Varian (b)		27,812
		Analytical Instruments
				208,714
		>Contract Manufacturing: 0.6%
	1,570,000	Plexus (b)		53,710
		Electronic Manufacturing Services
	1,705,000	Jabil Circuit		43,648
		Electronic Manufacturing Services
	4,000,000	Sanmina - SCI (b)		18,400
		BackPlane & Electronic Manufacturing Services
				115,758
		Telecommunications
		>Telecommunication Services: 3.1%
	4,500,000	Crown Castle International (b)		155,430
		Communication Towers
	3,500,000	American Tower (b)		108,920
		Communication Towers in USA & Mexico
	1,600,000	Alltel		102,129
		Cellular & Wireline Telephone Services
	4,250,000	Time Warner Telecom (b)(c)		63,113
		Fiber Optic Data/Telephone Service Provider
	8,000,000	Dobson Communications (b)(c)		61,840
		Rural & Small City Cellular Telephone Services
	780,000	Telephone and Data Systems		32,292
	300,000	Telephone and Data Systems, Cl. S		11,670
		Cellular & Wireline Telephone Services
	2,300,000	Tele2 AB (Sweden)		23,209
		European Mobile Operator & Services Reseller

Columbia Acorn Fund

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Telecommunication Services—continued
	200,000	Commonwealth Telephone	$	6,632
		Rural Phone Franchises & Competitive Telco
				565,235
		>Telecommunications Equipment: 0.9%
	10,000,000	Tellabs (b)		133,100
		Telecommunications Equipment
	1,380,000	Andrew (b)		12,227
		Wireless Infrastructure Equipment
	1,510,000	Symmetricom (b)		10,676
		Network Timing & Synchronization Devices
				156,003
		Media
		>Television Programming/CATV: 1.8%
	4,015,000	Discovery Holding (b)		58,739
		CATV Programming
	70,000	Jupiter Telecommunications (Japan) (b)		48,526
		Largest Cable Service Provider in Japan
	2,050,000	Liberty Global, Series C (b)		42,169
	1,750,000	Liberty Global, Series A (b)		37,625
		CATV Holding Company
	1,423,100	Alliance Atlantis Communication (Canada) (b)		41,687
		CATV Channels, TV/Movie Production/Distribution
	8,000,000	Gemstar-TV Guide International (b)		28,160
		TV Program Guides & CATV Programming
	3,000,000	Lions Gate Entertainment (b)		25,650
		Film & TV Studio
	655,000	Liberty Media - Interactive (b)		11,305
	130,000	Liberty Media - Capital (b)		10,890
		CATV Programming & Media Company Holdings
	1,250,000	Mediacom Communications (b)		7,787
		Cable Television Franchises
	700,000	Outdoor Channel (b)		7,224
		Cable Television Programming
				319,762
		>TV/Satellite Broadcasting: 0.4%
	2,752,829	SES Global (France)		39,212
		Satellite Broadcasting Services
	2,500,000	Entravision Communications (b)		21,425
		Spanish Language TV, Radio & Outdoor
	1,750,000	Gray Television		10,133
		Mid Market Affiliated TV Stations
	270,000	Metropole TV (France)		8,439
		Television Broadcaster
				79,209
		>Radio Broadcasting: 0.3%
	1,541,000	Salem Communications (b)(c)		20,048
		Radio Stations for Religious Programming
	1,500,000	Cumulus Media, Cl. A (b)		16,005
		Radio Stations in Small Cities
	1,400,000	Saga Communications (b)(c)		12,684
		Radio Stations in Small & Mid-sized Cities

Number of Shares			Value (000)
	2,400,000	Spanish Broadcasting System (b)(c)	$	12,264
		Spanish Language Radio Stations
				61,001
		Information: Total		4,085,985
Consumer Goods/Services: 18.5%
		Services
		>Retail: 5.3%
	5,960,000	Chico's FAS (b)		160,801
		Women's Specialty Retail
	2,200,000	Abercrombie & Fitch		121,946
		Teen Apparel Retailer
	2,760,000	Michaels Stores		113,822
		Craft & Hobby Specialty Retailer
	3,743,000	Christopher & Banks (c)		108,547
		Women's Apparel Retailer
	3,900,000	Urban Outfitters (b)		68,211
		Apparel & Home Specialty Retailer
	1,223,000	Ann Taylor Stores (b)		53,054
		Women's Apparel Retailer
	1,400,000	Williams Sonoma		47,670
		Home Goods & Furnishing Retailer
	2,250,000	Petco Animal Supplies (b)		45,968
		Pet Supplies & Services
	8,000,000	Rite Aid (b)		33,920
		Drug Stores
	1,100,000	J Crew Group (b)		30,195
		Multi-Channel Branded Retailer
	1,630,000	Rona (Canada) (b)		29,277
		Leading Canadian DIY Retailer
	936,000	Aeropostale (b)		27,041
		Mall Based Teen Retailer
	1,450,000	Borders Group		26,767
		Bookstores
	775,000	Genesco (b)		26,249
		Multi-Concept Branded Footwear Retailer
	750,000	Chattem (b)		22,778
		Personal Care Products
	1,062,000	Gaiam (b)(c)		14,889
		Healthy Living Catalogs & E-Commerce
	3,500,000	Edgars Consolidated Stores (South Africa)		14,109
		Leading Retail Conglomerate
				945,244
		>Consumer Services: 2.2%
	2,250,000	ITT Educational Services (b)(c)		148,073
		Post-secondary Degree Programs
	2,190,000	Pool Corporation		95,550
		Distributor of Swimming Pool Supplies and Equipment
	1,275,000	Weight Watchers		52,135
		Weight Loss Programs
	800,000	Regis Corp Minnesota		28,488
		Hair Salons
	1,530,000	Central Parking		24,480
		Owner, Operator & Manager of Parking Lots & Garages

1-800-922-6769

Number of Shares			Value (000)
		>Consumer Services—continued
	1,000,000	Universal Technical Institute (b)	$	22,020
		Vocational Training
	2,550,000	Princeton Review (b)(c)		13,566
		College Preparation Courses
	470,000	ServiceMaster		4,855
		Lawn Care, Pest Control, Commercial Disaster Response
	277,000	Lincoln Technical Institute (b)		4,734
		Vocational Training
	154,000	Park 24 (Japan)		4,523
		Parking Lot Operator
				398,424
		>Travel: 1.4%
	2,110,000	Vail Resorts (b)(c)		78,281
		Ski Resort Operator & Developer
	915,000	Four Seasons Hotels (Canada)		56,218
		Luxury Hotel Operator
	3,500,000	Expedia (b)		52,395
		Online Travel Service Company
	900,000	Intrawest (Canada)		28,444
		Ski Resort Operator & Developer
	270,000	Kerzner International (Bahamas) (b)		21,406
		Destination Resorts & Casinos
	1,045,000	Navigant International (b)(c)		16,751
		Corporate Travel Agency
	168,800	Localiza Rent A Car (Brazil)		3,234
		Car Rental
				256,729
		>Entertainment/Leisure Products: 1.1%
	1,795,000	RC2 (b)(c)		69,395
		Toys, Infant Products & Collectibles
	1,416,000	Speedway Motorsports		53,440
		Motorsport Racetrack Owner & Operator
	1,025,000	International Speedway Motors		47,529
		Largest Motorsport Racetrack Owner & Operator
	441,000	Thor Industries		21,366
		RV & Bus Manufacturer
	600,000	Callaway Golf		7,794
		Premium Golf Clubs & Balls
				199,524
		>Casinos & Gaming: 0.9%
	1,000,000	Station Casinos		68,080
		Casinos & Riverboats
	1,898,000	Pinnacle Entertainment (b)		58,174
		Regional Riverboat Casinos
	690,000	Intralot (Greece)		18,463
		Lottery & Gaming Systems & Services
	4,700,000	Sky City Entertainment (New Zealand)		15,448
		Casino/Entertainment Complex
	226,000	Lakes Entertainment (b)		2,732
		Native American Casino Development
				162,897
		>Restaurants: 0.7%
	2,145,000	Sonic (b)		44,595
		Quick Service Restaurant
	1,000,000	Red Robin Gourmet Burgers (b)(c)		42,560
		Casual Dining Restaurants

Number of Shares			Value (000)
	800,000	Cheesecake Factory (b)	$	21,560
		Casual Dining Restaurants
	1,600,000	AFC Enterprises (c)		20,400
		Popeye's Restaurants
				129,115
		>Cruise Lines: 0.1%
	400,000	Carnival		16,696
		Largest Cruise Line
		Goods
		>Apparel: 1.8%
	6,980,000	Coach (b)		208,702
		Designer & Retailer of Branded Leather Accessories
	1,418,000	Carter's (b)		37,478
		Children's Branded Apparel
	919,000	Oxford Industries (c)		36,218
		Branded & Private Label Apparel
	3,000,000	Billabong International (Australia)		34,250
		Action Sports Apparel Brand Manager
	700,000	True Religion Apparel (b)		12,390
		Premium Denim
				329,038
		>Furniture/Textiles: 1.7%
	2,550,000	HNI		115,643
		Office Furniture & Fireplaces
	765,000	Mohawk Industries (b)		53,818
		Carpet & Flooring
	2,068,000	Herman Miller		53,292
		Office Furniture
	1,398,000	Nobia (Sweden)		45,347
		Kitchen Cabinet Manufacturing & Distribution
	1,435,000	Knoll		26,347
		Office Furniture
				294,447
		>Leisure Vehicles: 1.2%
	1,751,000	Harley-Davidson		96,112
		Motorcycles & Related Merchandise
	1,130,000	Polaris Industries		48,929
		Leisure Vehicles & Related Products
	4,690,000	Fleetwood Enterprises (b)(c)		35,363
		RV & Manufactured Home Maker
	690,000	Winnebago		21,418
		Premier Motorhome Maker
	5,700,000	Ducati Motor (Italy) (b)		4,839
		Motorcycles & Related Merchandise
				206,661
		>Nondurables: 1.0%
	2,620,000	Scotts Miracle-Gro		110,878
		Consumer Lawn & Garden Products
	1,000,000	Jarden (b)		30,450
		Branded Household Products
	1,886,000	Prestige Brands (b)		18,803
		OTC, Household & Personal Care Products
	1,100,000	Natura Cosmeticos (Brazil)		11,529
		Direct Retailer of Cosmetics
				171,660

Columbia Acorn Fund

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Durable Goods: 0.6%
	465,000	Hyundai Mobis (South Korea)	$	39,290
		Auto Parts
	1,800,000	Helen of Troy (b)(c)		33,120
		Hairdryers & Curling Irons
	14,999,300	Techtronic Industries (Hong Kong)		20,273
		Power Tools & Motorized Appliances
	900,000	Champion Enterprises (b)		9,936
		Manufactured Homes
	172,000	Cavco Industries (b)		7,644
		Higher End Manufactured Homes
	90,000	Shimano (Japan)		2,758
		Bicycle Components & Fishing Tackle
				113,021
		>Food & Beverages: 0.5%
	1,597,000	IAWS Group (Ireland)		28,157
		Baked Goods
	2,410,000	Davide Campari (Italy)		24,965
		Spirits & Wine
	2,500,000	C&C Group (Ireland)		21,711
		Beverage Company
	35,000,000	Global Bio-Chem Technology Group (China)		14,800
		Refiner of Corn-Based Commodities
				89,633
		Consumer Goods/Services: Total		3,313,089
Industrial Goods/Services: 17.9%
		>Industrial Goods/Services: 3.3%
	1,900,000	Genlyte Group (b)(c)		137,617
		Commercial Lighting Fixtures
	3,600,000	Donaldson		121,932
		Industrial Air Filtration
	3,222,000	Clarcor (c)		95,983
		Mobile & Industrial Filters
	1,900,000	Mine Safety Appliances (c)		76,380
		Safety Equipment
	750,000	W.W. Grainger		56,422
		Industrial Distribution
	1,048,000	Drew Industries (b)		33,955
		RV & MFG Home Components
	1,600,000	Goodman Global (b)		24,288
		HVAC Equipment Manufacturer
	1,125,000	Ushio (Japan)		23,823
		Industrial Light Sources
	700,000	Legrand (France)		19,691
		Electrical Components
	141,000	Electric City (b)		155
		Electricity Conservation Devices
				590,246
		>Machinery: 3.2%
	2,200,000	Esco Technologies (b)(c)		117,590
		Automatic Electric Meter Readers
	2,350,000	Ametek		111,343
		Aerospace/Industrial Instruments
	2,750,000	Pentair		94,022
		Pumps, Water Treatment & Tools
	2,000,000	Gardner Denver (b)		77,000
		Air Compressors, Blowers & Pumps

Number of Shares			Value (000)
	1,500,000	Nordson	$	73,770
		Dispensing Systems for Adhesives & Coatings
	1,100,000	Kaydon		41,041
		Specialized Friction & Motion Control Products
	522,000	Toro		24,377
		Turf Maintenance Equipment
	1,187,000	K&F Industries Holdings (b)		21,046
		Aircraft Wheels, Brakes & Fuel Tank Bladders
	212,000	Oshkosh Truck		10,074
		Specialty Truck Manufacturer
				570,263
		>Logistics: 2.6%
	5,500,000	Expeditors International of Washington		308,055
		International Freight Forwarder
	2,000,000	Forward Air (c)		81,460
		Freight Transportation Between Airports
	3,000,000	UTI Worldwide		75,690
		Global Logistics & Freight Forwarding
				465,205
		>Industrial Distribution: 1.8%
	2,286,000	Watsco (c)		136,749
		HVAC Distribution
	1,925,000	Airgas		71,706
		Industrial Gas Distributor
	1,150,000	Aviall (b)		54,648
		Aircraft Replacement Parts Distributor
	3,500,000	Grafton Group (Ireland)		44,057
		Building Materials Wholesaling & DIY Retailing
	1,031,000	Nuco2 (b)(c)		24,785
		Bulk CO2 Gas Distribution to Restaurants
				331,945
		>Construction: 1.8%
	1,900,000	Florida Rock Industries		94,373
		Concrete & Aggregates
	2,200,000	Simpson Manufacturing		79,310
		Wall Joint Maker
	605,000	Martin Marietta		55,146
		Aggregates
	42,500	Geberit (Switzerland)		49,104
		Plumbing Supplies
	380,000	Daito Trust Construction (Japan)		21,128
		Apartment Builder
	1,000,000	Kingspan Group (Ireland)		17,459
		Building Insulation & Environmental Containers
	90,000	Ciments Francais (France)		14,962
		Leading French & Emerging Markets Cement Producer
				331,482
		>Steel: 1.3%
	2,860,000	Gibraltar Industries (c)		82,940
		Steel Processing
	1,500,000	Tenaris (Argentina)		60,735
		Oil, Gas & Industrial Seamless Tubes
	2,160,000	Worthington Industries		45,252
		Steel Processing

1-800-922-6769

Number of Shares			Value (000)
		>Steel—continued
	33,000	Vallourec (France)	$	39,673
		Oil, Gas & Industrial Seamless Tubes
				228,600
		>Specialty Chemicals & Industrial Materials: 1.2%
	2,800,000	Spartech (c)		63,280
		Plastics Distribution & Compounding
	730,000	Novozymes (Denmark)		49,201
		Industrial Enzymes
	28,000	Sika (Switzerland)		31,105
		Chemicals for Construction & Industrial Application
	400,000	Carbone Lorraine (France)		21,994
		Advanced Industrial Materials
	200,000	Imerys (France)		15,980
		Industrial Minerals Producer
	20,000	Givaudan (Switzerland)		15,728
		Fragrances & Flavors
	430,768	Koninklijke Ten Cate (Netherlands)		12,646
		Advanced Textiles & Industrial Fabrics
	438,000	Ultrapar (Brazil)		6,896
		Specialty Chemicals & Liquid Propane Gas Distribution
				216,830
		>Outsourcing Services & Training: 1.0%
	650,000	USG People (Netherlands)		49,754
		Temporary Staffing Services
	2,500,000	Quanta Services (b)		43,325
		Electrical & Telecom Construction Services
	1,100,000	Administaff		39,391
		Professional Employer Organization
	1,600,000	Labor Ready (b)		36,240
		Temporary Manual Labor
	600,000	GP Strategies (b)		4,626
		Training Programs
				173,336
		>Conglomerates: 0.6%
	765,342	Aalberts Industries (Netherlands)		56,261
		Flow Control & Heat Treatment
	1,325,058	Hexagon (Sweden)		48,238
		Measurement Equipment & Polymers
				104,499
		>Water: 0.6%
	2,500,000	Pall		70,000
		Filtration & Fluids Clarification
	900,000	Watts Water Technologies		30,195
		Water, Valves, Regulators & Filtration
				100,195
		>Other Industrial Services: 0.5%
	1,650,000	Mobile Mini (b)		48,279
		Portable Storage Unit Leasing
	374,000	IM Tech (Netherlands)		18,054
		Engineering & Technical Services
	655,000	Tal International (b)		15,786
		Intermodal Freight Container Leasing
	740,000	Jaakko Poyry (Finland)		7,956
		Engineering Consultants in Forestry, Energy
				90,075
		Industrial Goods/Services: Total		3,202,676

Number of Shares			Value (000)
Finance: 12.3%
		>Banks: 4.3%
	2,505,000	BOK Financial	$	124,423
		Tulsa Based S.W. Bank
	3,600,000	Associated Banc-Corp		113,508
		Midwest Bank
	3,156,000	TCF Financial		83,476
		Great Lakes Bank
	2,720,000	Glacier Bancorp (c)		79,614
		Mountain States Bank
	3,500,000	Anglo Irish Bank (Ireland)		54,536
		Small Business & Middle Market Banking
	2,850,000	Northern Rock (United Kingdom)		52,637
		Lowest Cost Mortgage Bank in UK
	1,320,000	West Coast Bancorp (c)		38,900
		Portland Small Business Lender
	2,275,000	Depfa Bank (Germany)		37,713
		Investment Banker to Public Authorities
	250,000	Komercni Banka (Czech Republic)		36,578
		Leading Czech Universal Bank
	590,000	CityBank Lynnwood (c)		27,529
		Seattle Real Estate Lender
	796,000	Great Southern Bancorp (c)		24,302
		Missouri Real Estate Lender
	892,000	Chittenden		23,058
		Vermont & Western Massachusetts Bank
	886,000	West Bancorporation (c)		16,542
		Des Moines Commercial Bank
	400,000	East West Bancorp		15,164
		LA Bank with Chinese Focus
	406,000	First Financial BankShares		14,835
		West Texas Bank
	500,000	Cascade Bancorp		14,255
		Central Oregon Bank
	304,000	S Y Bancorp		8,354
		Louisville Bank
	313,000	First Mutual Bancshares (c)		8,154
		Seattle Community Bank
	150,000	Greene County Bancshares		4,644
		Tennessee Bank
				778,222
		>Insurance: 3.1%
	2,040,000	Philadelphia Consolidated Holding (b)		61,934
		Specialty Insurance
	2,030,000	HCC Insurance Holdings		59,763
		Specialty Insurance
	1,200,000	Assurant		58,080
		Specialty Insurance
	1,748,000	Leucadia National		51,024
		Insurance Holding Company
	995,000	Protective Life		46,387
		Life Insurance
	710,000	Selective Insurance Group		39,668
		Commercial & Personal Lines Insurance
	109,000	Markel (b)		37,823
		Specialty Insurance
	1,550,000	United America Indemnity (b)(c)		32,302
		Specialty Insurance
	940,000	Endurance Specialty Holdings		30,080
		Commercial Lines Insurance/Reinsurance

Columbia Acorn Fund

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Insurance—continued
	1,700,000	Scottish Re Group	$	28,254
		Life Reinsurance
	570,000	RLI		27,463
		Specialty Insurance
	750,000	Delphi Financial Group		27,270
		Group Employee Benefit Products and Services
	600,000	National Financial		26,586
		Distributor of Life Insurance, Group Benefits & Inv adv svs
	520,000	StanCorp Financial		26,473
		Group Life & Disability Insurance
				553,107
		>Brokerage & Money Management: 1.8%
	2,464,000	SEI Investments		120,440
		Mutual Fund Administration & Investment Management
	3,970,000	Eaton Vance		99,091
		Specialty Mutual Funds
	1,757,000	Nuveen Investments		75,638
		Specialty Mutual Funds
	350,000	Investment Technology Group (b)		17,801
		Electronic Trading
				312,970
		>Finance Companies: 1.7%
	6,500,000	AmeriCredit (b)		181,480
		Auto Lending
	1,700,000	World Acceptance (b)(c)		60,384
		Personal Loans
	930,000	McGrath Rentcorp		25,863
		Temp Space & IT Equipment Rental
	1,120,000	Paragon Group (United Kingdom)		13,517
		UK Buy-to-Let Finance Company
	832,000	Electro Rent (b)		13,329
		Test & Measurement Rentals
	263,000	Marlin Business Services (b)		5,933
		National Small Equipment Leasing
	80,000	American Banknote (Brazil) (b)		517
		Manufacturer of Smart Cards
				301,023
		>Savings & Loans: 1.4%
	4,196,000	Peoples Bank Bridgeport		137,839
		Connecticut Savings & Loan
	1,700,000	Housing Development Finance (India)		41,847
		Premier Mortgage Lender in India
	1,178,000	Anchor Bancorp Wisconsin (c)		35,540
		Wisconsin Thrift
	1,285,000	Washington Federal		29,799
		Traditional Thrift
	360,000	Provident Bancorp		4,759
		New York State Thrift
				249,784
		Finance: Total		2,195,106
Energy/Minerals: 9.8%
		>Oil/Gas Producers: 5.0%
	3,200,000	Western Gas Resources		191,520
		Oil & Coal Seam Gas Producer

Number of Shares			Value (000)
	2,700,000	Ultra Petroleum (b)	$	160,029
		Natural Gas Producer
	2,500,000	XTO Energy		110,675
		Natural Gas Producer
	13,500,000	Tullow Oil (United Kingdom)		95,191
		Oil & Gas Producer
	4,900,000	Talisman Energy (Canada)		85,507
		Oil & Gas Producer
	2,400,000	Equitable Resources		80,400
		Natural Gas Producer & Utility
	2,000,000	Southwestern Energy (b)		62,320
		Natural Gas Producer
	1,500,000	Range Resources		40,785
		Oil & Gas Producer
	3,200,000	Vaalco Energy (b)(c)		31,232
		Oil & Gas Producer
	700,000	Denbury Resources (b)		22,169
		Oil Producer Using CO₂ Injection
	1,200,000	McMoran Exploration (b)		21,120
		Natural Gas Producer & Developer
	150,000	Hugoton Royalty		4,455
		Oil & Gas Producer
				905,403
		>Oil Services: 3.6%
	2,350,000	FMC Technologies (b)		158,531
		Oil & Gas Well Head Manufacturer
	2,728,301	Fugro (Netherlands)		117,626
		Survey & GPS Services
	2,300,000	Pride International (b)		71,829
		Offshore Drilling Contractor
	1,000,000	Atwood Oceanics Inc (b)		49,600
		Contract Drilling
	750,000	Carbo Ceramics		36,848
		Natural Gas Well Stimulants
	2,400,000	Key Energy Services (b)		36,600
		Well Workover Services
	971,000	Rowan		34,557
		Offshore Drilling Contractor
	1,193,000	Chicago Bridge & Iron		28,811
		Engineering & Construction for Petrochemicals & LNG
	1,140,000	Enerflex Systems (Canada) (c)		28,441
		Natural Gas Compresser Rental & Fabrication
	1,200,000	Saipem (Italy)		27,284
		Offshore Construction & Drilling
	350,000	Veritas DGC (b)		18,053
		Geophysical Contractor
	2,860,000	Newpark Resources (b)		17,589
		Drilling Fluid Services
	257,000	Helmerich & Payne		15,487
		Contract Driller
				641,256
		>Mining: 0.7%
	900,000	Falconbridge (Canada)		47,407
		Diversified Mining Holding Company
	13,100,000	UrAsia Energy (Canada)		32,859
		Uranium Mining in Kazakhstan
	195,000	Sociedad Quimica Y Minera de Chile (Chile)		20,307
		Producer of Specialty Fertilizers, Lithium & Iodine

1-800-922-6769

Number of Shares			Value (000)
		>Mining—continued
	2,900,000	Jubilee Gold Mines (Australia)	$	17,384
		Nickel Mining in Australia
	1,000,000	Ivanhoe Mines (Canada) (b)		6,772
		Copper Mining in Mongolia
				124,729
		>Distribution/Marketing/Refining: 0.3%
	966,000	Atmos Energy		26,961
		Dallas Natural Gas Utility
	600,000	Maritrans		14,940
		Shipping
	435,000	Oneok		14,807
		Natural Gas Distribution, Pipeline, Processing & Trading
				56,708
		>Agricultural Commodities: 0.2%
	550,000	Aracruz Celulose (Brazil)		28,831
		Brazilian Hardwood Pulp Producer
		Energy/Minerals: Total		1,756,927
Health Care: 7.8%
		>Medical Equipment/ Laboratory Supplies: 3.1%
	1,910,000	CYTYC (b)		48,438
		Consumables Related to Women's Health
	475,000	Essilor International (France)		47,764
		Eyeglass Lenses
	1,770,000	Intermagnetics General (b)		47,755
		MRI Equipment
	800,000	Diagnostic Products		46,536
		Immunodiagnostic Kits
	1,000,000	Edwards Lifesciences (b)		45,430
		Heart Valves
	870,000	Vital Signs (c)		43,091
		Anesthesia, Respiratory & Sleep Products
	1,000,000	ICU Medical (b)(c)		42,240
		Intravenous Therapy Products
	350,000	Synthes (Switzerland)		42,169
		Products for Orthopedic Surgery
	905,000	Arrow International		29,747
		Disposable Catheters
	552,000	Advanced Medical Optics (b)		27,986
		Medical Devices for Eye Care
	875,000	Viasys Healthcare (b)		22,400
		Respiratory & Neurology Medical Equipment
	583,000	Orthofix International (b)		22,230
		Bone Fixation & Stimulation Devices
	1,250,000	PSS World Medical (b)		22,063
		Medical Supplies Distributor
	390,000	Hogy Medical (Japan)		20,496
		Disposable Surgical Products
	415,000	Cooper		18,380
		Contact Lens Manufacturer
	350,000	Haemonetics (b)		16,279
		Blood & Plasma Collection Equipment
	455,000	Datascope		14,032
		Medical Devices
				557,036

Number of Shares			Value (000)
		>Services: 2.6%
	2,491,000	Lincare Holdings (b)	$	94,259
		Home Health Care Services
	1,232,000	Coventry Health Care (b)		67,686
		HMO
	1,607,000	Serologicals (b)		50,524
		Blood Collection & Antibody Production
	1,355,000	Charles River Laboratories (b)		49,864
		Pharmaceutical Research
	875,000	LCA Vision		46,296
		Lasik Surgery Centers
	1,000,000	Rhoen-Klinikum (Germany)		44,535
		Healthcare Services
	510,000	OPG Groep (Netherlands)		44,300
		Healthcare Supplies & Pharmacies
	900,000	United Surgical Partners (b)		27,063
		Outpatient Surgery Center
	808,000	PRA International (b)		17,994
		Contract Research Organization
	1,433,000	Dendrite International (b)		13,241
		Software for Pharmaceutical Sales Force Automation
	1,050,000	Eresearch Technology (b)		9,555
		Clinical Research Services
	500,000	Merge Technologies (b)		6,155
		Radiology Information Systems
				471,472
		>Biotechnology/Drug Delivery: 1.7%
	3,230,000	Exelixis (b)		32,461
		Treatments for Cancer & Metabolic Disorders
	1,360,000	Nektar Therapeutics (b)		24,942
		Drug Delivery Technologies
	2,380,000	Ligand Pharmaceuticals (b)		20,111
		Drugs for Pain, Cancer, Osteoporosis, & Diabetes
	2,000,000	Medarex (b)		19,220
		Humanized Antibodies
	1,650,000	Human Genome Sciences (b)		17,655
		Drug Discovery/Development
	1,100,000	Renovis (b)		16,841
		Drug to Minimize Neurological Damage from Strokes
	1,429,000	Arena Pharmaceuticals (b)		16,548
		Novel Drug Targeting Technology
	1,135,000	Keryx Biopharmaceuticals (b)		16,117
		Drugs for Diabetic Complications & Cancer
	2,520,000	Decode Genetics (b)		15,599
		Drugs for Heart Attack, Asthma & Vascular Disease
	1,780,000	Array Biopharma (b)		15,308
		Drugs for Cancer & Inflammatory Diseases
	930,000	Intermune (b)		15,299
		Drugs for Hepatitis C, Pulmonary Fibrosis & Cancer
	3,100,000	Lexicon Genetics (b)		13,609
		Drug Discovery
	2,000,000	Cytokinetics (b)(c)		12,580
		Drugs for Cancer & Heart Failure
	1,275,000	Rigel Pharmaceuticals (b)(c)		12,406
		Drugs for Hay Fever, Asthma, Hepatitis & Cancer

Columbia Acorn Fund

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Biotechnology/Drug Delivery—continued
	1,585,000	Maxygen (b)	$	11,856
		Molecular Breeding
	1,750,000	Genitope (b)		11,060
		Cancer Vaccine
	2,300,000	Seattle Genetics (b)		10,580
		Antibody-Based Therapies for Cancer
	800,000	Momenta Pharmaceuticals (b)		10,168
		Sugar Analysis Technology for Drug Design
	1,500,000	Tercica (b)		7,935
		Drug to Treat Severe Short Stature In Children
	1,100,000	La Jolla Pharmaceutical (b)		4,037
		Lupus Treatment
	1,249,999	Perlegen Sciences (d)		3,375
		Large Scale Gene Sequencing
	1,875,000	Locus Discovery, Series D, Pfd. (d)		512
		High Throughput Rational Drug Design
	359,944	Microdose (d)		360
		Drug Inhalers
				308,579
		>Medical Supplies: 0.4%
	486,000	Techne (b)		24,747
		Cytokines, Antibodies, Other Reagents For Life Sciences
	650,000	Owens & Minor		18,590
		Distribution of Medical Supplies
	4,000,000	United Drug (Ireland)		17,129
		Irish Pharmaceutical Wholesaler & Outsourcer
				60,466
		Health Care: Total		1,397,553
Other Industries: 4.7%
		>Real Estate: 3.6%
	5,850,000	Highland Hospitality (c)		82,368
		Hotel Owner
	650,000	SL Green Realty		71,155
		Manhattan Office Buildings
	1,398,000	Forest City Enterprises, Cl. B (c)		69,578
		Commercial & Residential Property Developer
	1,560,000	Gaylord Entertainment (b)		68,078
		Convention Hotels
	1,320,000	General Growth Properties		59,479
		Regional Shopping Malls
	3,294,000	DiamondRock Hospitality (c)		48,784
	1,000,000	DiamondRock Hospitality 144A (c)(d)		14,810
		Hotel Owner
	635,000	Macerich Company		44,577
		Regional Shopping Malls
	575,000	Federal Realty Investment Trust		40,250
		Shopping Centers
	1,020,000	Brandywine Realty		32,813
		Office Buildings
	1,720,000	Kite Realty Group (c)		26,815
		Community Shopping Centers
	1,375,000	Crescent Real Estate Equities		25,520
		Class A Office Buildings
	536,000	Parkway Properties		24,388
		Office Buildings

Number of Shares or Principal Amount			Value (000)
	900,000	American Campus Communities (c)	$	22,365
		Student Housing
	4,100	Kenedix (Japan)		17,754
		Real Estate Investment Management
	37,407	Security Capital European Realty (Luxembourg) (d)		531
		Self Storage Properties
				649,265
		>Transportation: 0.5%
	1,584,000	Heartland Express		28,338
		Regional Trucker
	1,086,000	JB Hunt		27,052
		Trucking Conglomerate
	760,000	Grupo Aeroportaurio Del Sureste (Mexico)		25,528
		Cancun & Cozumel Airport Operator
				80,918
		>Waste Management: 0.3%
	1,700,000	Waste Connections (b)		61,880
		Solid Waste Management
		>Regulated Utilities: 0.3%
	1,650,000	Northeast Utilities		34,106
		Regulated Electric Utility
	589,800	Red Electrica (Spain)		20,338
		Spanish Power Grid
				54,444
		Other Industries: Total		846,507
	Total Common Stocks and Other Equity-Like Securities: 93.8% (e) (Cost: $10,141,998)			16,797,843
Short-Term Obligations: 6.3%
$	176,000	Verizon Global Funding 5.18% - 5.35% Due 8/2/06 - 8/17/06		175,002
	161,000	HSBC Finance Corporation 5.04% - 5.05% Due 7/14/06 - 7/27/06		160,559
	155,000	American General Finance 5.01% - 5.06% Due 7/6/06 - 7/19/06		154,783
	154,000	Aluminum Company America 5.08% - 5.26% Due 7/3/06 - 8/9/06		153,478
	145,000	Credit Suisse First Boston 5.05% - 5.28% Due 7/13/06 - 8/11/06		144,325
	91,755	Hartford Financial 5.11% - 5.28% Due 7/28/06 - 8/10/06		91,319
	67,000	Conocophillips 5.09% Due 7/21/06 - 7/25/06		66,790
	60,000	Countrywide Financial Funding 5.30% - 5.40% Due 8/16/06		59,772
	40,000	Citigroup Funding 5.02% Due 08/01/06		39,823

1-800-922-6769

Principal Amount			Value (000)
		>Short-Term Obligations—continued
$	32,000	American Express Credit Corp 5.03% Due 7/10/06	$	31,960
	29,000	Bell South Corp 5.02% Due 7/12/06		28,983
	23,140	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/3/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 5/22/08 market value $23,605 (repurchase proceeds: $23,150)		23,140
		(Amortized Cost: $1,129,934)		1,129,934
	Total Investments: 100.1% (Cost: $11,271,932)(a)			17,927,777
	Cash and Other Assets Less Liabilities: (0.1%)			(11,701	)
	Total Net Assets: 100%		$	17,916,076

Columbia Acorn Fund

>Statement of Investments (Unaudited), continued

>Notes to Statement of Investments (in thousands)

(a) At June 30, 2006, for federal income tax purposes cost of investments was $11,271,932 and net unrealized appreciation was $6,655,845 consisting of gross unrealized appreciation of $7,119,226 and gross unrealized depreciation of $463,381.

(b) Non-income producing security.

(c) An affiliate may include any company in which the Fund owns five percent or more of its outstanding voting shares. On June 30, 2006, the Fund held five percent or more of the outstanding voting securities of the following companies:

AnswerThink Consulting					10.31
Christopher & Banks					10.25
Actuate					9.95
Highland Hospitality					9.79
Gibraltar Industries					9.60
Watsco					9.52
Indus International					9.49
Igate Capital					9.44
Princeton Review					9.24
World Acceptance					9.19
Skillsoft Publishing					8.79
Spartech					8.72
RC2					8.61
West Coast Bancorp					8.60
Kronos					8.58
Esco Technologies					8.53
Glacier Bancorp					8.41
Salem Communications					8.19
Saga Communications					7.69
Bally Technologies					7.48
Fleetwood Enterprises					7.35
ICU Medical					7.00
Concurrent Computer					6.92
Shuffle Master					6.92
Genlyte Group					6.75
Proquest Company					6.69
Nuco2					6.64
Vital Signs					6.61
Seachange International					6.55
Tumbleweed Communications					6.49
II VI					6.43
United America Indemnity					6.41
Forward Air					6.35
Navigant International					6.24
Clarcor					6.20
DiamondRock Hospitality					6.12
Red Robin Gourmet Burgers					6.04
Kite Realty Group					6.01
Helen of Troy					5.99
Spanish Broadcasting System					5.95
First Mutual Bancshares					5.88
Great Southern Bancorp					5.79
CityBank Lynnwood					5.67
IXYS					5.57
Time Warner Telecom					5.57
Vaalco Energy					5.55
Cytokinetics					5.48
Vail Resorts					5.41
Forest City Enterprises Class B					5.39
Anchor Bancorp Wisconsin					5.36
AFC Enterprises					5.35
Dobson Communications					5.31
West Bancorporation					5.30
American Campus Communities					5.23
Oxford Industries					5.21
Mine Safety Appliances					5.19
Excel Technologies					5.18
Gaiam					5.16
ITT Educational Services					5.14
Rigel Pharmaceuticals					5.13
JDA Software					5.10
Supertex					5.04
Enerflex Systems					5.02

The aggregate cost and value of these companies at June 30, 2006, was $1,819,627 and $2,934,084 respectively. Investments in affiliate companies represent 16.28% of total net assets at June 30, 2006. Investment activity and income amounts relating to affiliates during the six months ended June 30, 2006 were as follows:

Dividend income	$	13,299
Net realized gain or loss		—
Change in unrealized gain or loss		253,598
Purchases		262,161
Proceeds from sales		13,003

In addition, additional purchases of existing portfolio holdings that were not considered affiliates in prior years, resulted in the fund owning more than 5% of the outstanding shares of certain issues at June 30, 2006. Therefore, the cost and market value affiliate disclosure amounts include both acquisitions of new investments in affiliates during the period, as well as prior period investment holdings that became affiliates during the current period.

1-800-922-6769

(d) Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities, except for DiamondRock Hospitality, are valued in good faith by the Board of Trustees. At June 30, 2006, these securities (in thousands) amounted to $19,588, which represents 0.11% of total net assets.

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost (000)		Value (000)
DiamondRock Hospitality 144A	06/29/04		1,000,000	$	10,000	$	14,810
Perlegen Sciences	03/30/01		1,249,999		4,500		3,375
Security Capital European Realty (Luxembourg)	08/20/98 - 11/12/99		37,407		748		531
Locus Discovery, Series D Pfd.	09/05/01		1,875,000		7,500		512
Microdose	11/24/00		359,944		2,005		360
				$	24,753	$	19,588

(e) On June 30, 2006, the market value of foreign securities (in thousands) represents 13.70% of total net assets. The Fund's foreign portfolio was diversified as follows:

	Value		Percent
Canada	$	356,612		1.99	%
Netherlands		298,641		1.67
France		236,584		1.32
Ireland		183,049		1.02
United Kingdom		161,345		0.90
Japan		139,008		0.78
Switzerland		138,106		0.77
Sweden		116,794		0.65
Germany		111,615		0.62
Hong Kong		62,049		0.35
Luxembourg		61,266		0.34
Taiwan		59,483		0.33
Italy		57,088		0.32
Australia		51,635		0.29
Brazil		51,007		0.29
	Value		Percent
Denmark	$	49,201		0.28	%
Israel		45,981		0.26
India		41,847		0.23
South Korea		39,290		0.22
Czech Republic		36,578		0.20
Mexico		25,528		0.14
Bahamas		21,406		0.12
Spain		20,338		0.11
Chile		20,307		0.11
Greece		18,463		0.10
New Zealand		15,448		0.09
China		14,800		0.08
South Africa		14,109		0.08
Finland		7,956		0.04
Total Foreign Portfolio	$	2,455,534		13.70	%

Columbia Acorn International

>Major Portfolio Changes in the Second Quarter (Unaudited)

	Number of Shares
	03/31/06		06/30/06
Additions
Europe
>France
Carbone Lorraine		340,000		395,000
Eurofins Scientific		320,000		360,000
Foncia Groupe		0		400,000
Legrand		0		700,000
Neopost		236,000		280,000
Norbert Dentressangle		300,000		375,000
Trigano		423,000		500,000
>United Kingdom
Randgold Resources		0		640,000
UTV		1,800,000		2,000,000
>Netherlands
Aalberts Industries		550,000		557,534
Fugro		1,245,000		1,268,491
IM Tech		474,000		574,000
>Germany
Depfa Bank		1,675,000		2,000,000
Rational AG		0		75,000
>Switzerland
Givaudan		15,000		25,000
Kuehne & Nagel		95,000		475,000
Synthes		215,000		275,000
>Italy
Amplifon		1,700,000		2,000,000
(includes the effect of a 10 for 1 stock split)
Cir Compagnie		6,000,000		9,100,000
Ducati Motor		6,400,000		12,800,000
GranitiFiandre		275,000		1,223,000
>Sweden
Sweco		380,000		422,000
Tele2		2,100,000		2,580,000
>Poland
Central European Distribution		448,000		820,500
(includes the effect of a 3 for 2 stock split)

	Number of Shares
	03/31/06		06/30/06
Asia
>Japan
FCC		454,000		714,000
Kansai Paint		882,000		3,700,000
Sparx Asset Management		0		22,500
Other Countries
>Canada
Alliance Atlantis Communication		639,000		1,060,000
UrAsia Energy		0		1,475,000
Van Houtte		0		950,000
>Australia
Sino Gold		0		5,450,000
>South Africa
Impala Platinum		140,000		180,000
>United States
Atwood Oceanics		0		415,000
>New Zealand
Sky City Entertainment		5,000,000		5,500,000
Latin America
>Brazil
American Banknote		0		1,085,000
Localiza Rent a Car		0		170,000
Suzano		3,215,000		4,300,000

1-800-922-6769

	Number of Shares
	03/31/06		06/30/06
Sales
Europe
>France
Essilor International		300,000		200,000
Vallourec		20,000		0
>United Kingdom
Bloomsbury Publishing		2,000,000		916,000
Intermediate Capital		600,000		0
Kensington Group		1,050,000		813,050
>Germany
Bilfinger Berger		300,000		200,000
>Ireland
Anglo Irish Bank		2,260,000		2,200,000
>Switzerland
BKW Energie		130,000		27,000
>Sweden
Gambro		2,042,000		0
>Spain
Abengoa		370,000		0
>Russia
RBC Information Systems		700,000		575,800

	Number of Shares
	03/31/06		06/30/06
Asia
>Japan
Meitec		475,000		0
Shimano		900,000		650,000
>Taiwan
Novatek Microelectronics		3,244,000		3,000,000
>Hong Kong
Hong Kong Exchanges and Clearing		6,000,000		5,000,000
Linmark Group		13,483,000		10,996,000
>South Korea
Samsung Fire & Marine		100,000		0
>Indonesia
Perusahaan Gas Negara		20,000,000		15,000,000
>Singapore
Comfort Del Gro		20,000,000		7,053,000
Other Countries
>Canada
Kinross Gold		1,100,000		835,000
>Australia
ABC Learning Center		4,028,250		4,000,000
Latin America
>Brazil
America Latina Logistics		280,000		0
Diagnosticos		590,000		392,000
Natura Cosmeticos		3,200,000		2,500,000
Porto Seguro		1,000,000		720,000
Ultrapar		500,000		293,000

Columbia Acorn International

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares			Value (000)
			Common Stocks: 95.9%
Europe: 59.2%
		>France: 11.5%
	700,000	April Group	$	37,576
		Insurance Policy Construction
	390,000	Iliad		32,484
		High Speed Internet Service Provider
	280,000	Neopost		31,875
		Postage Meter Machines
	2,200,000	SES Global		31,338
		Satellite Broadcasting Service
	411,000	Rubis		28,755
		Tank Storage & LPG Supplier
	500,000	Trigano		26,540
		Leisure Vehicles & Camping Equipment
	375,000	Norbert Dentressangle		26,380
		Transport
	360,000	Eurofins Scientific (b)		23,436
		Food Screening & Testing
	206,000	Pierre & Vacances		22,580
		Vacation Apartment Lets
	395,000	Carbone Lorraine		21,719
		Advanced Industrial Materials
	200,000	Essilor International		20,111
		Eyeglass Lenses
	120,000	Ciments Francais		19,949
		Leading French & Emerging Markets Cement Producer
	700,000	Legrand		19,691
		Electrical Components
	240,000	Imerys		19,176
		Industrial Minerals Producer
	151,000	Bacou Dalloz		17,981
		Safety Equipment
	400,000	Foncia Groupe		17,646
		Real Estate Services
	550,000	Metropole Television		17,190
		Television Broadcaster
				414,427
		>United Kingdom: 8.6%
	6,370,000	Tullow Oil		44,915
		Oil & Gas Producer
	1,850,000	Northern Rock		34,168
		Lowest Cost Mortgage Bank in UK
	2,800,000	Paragon Group		33,792
		Buy-To-Let Finance Company
	7,200,000	RPS Group		28,825
		Environmental Consulting & Planning
	1,850,000	Expro International Group		23,212
		Offshore Oilfield Services
	1,200,000	Northgate		23,211
		Light Commercial Vehicle Rental Specialist
	4,200,000	Taylor Nelson Sofres		18,065
		Market Research
	3,550,000	BBA Group		17,346
		Aviation Support Services & Non-Woven Materials
	2,450,000	Workspace Group		16,380
		Real Estate
	813,050	Kensington Group		15,460
		Non-Conforming Mortgage Company

Number of Shares			Value (000)
	1,300,000	Keller Group	$	13,967
		International Ground Engineering Specialist
	640,000	Randgold Resources (b)		13,440
		Gold Mining in Western Africa
	2,000,000	UTV		12,575
		Irish Television & Radio Station Operator
	450,000	Viridian Group		7,952
		Northern Ireland Electric Utility
	916,000	Bloomsbury Publishing		5,485
		Book Publisher
				308,793
		>Netherlands: 8.3%
	1,268,491	Fugro		54,689
		Survey & GPS Services
	679,000	USG People		51,973
		Temporary Staffing Services
	557,534	Aalberts Industries		40,985
		Flow Control & Heat Treatment
	972,304	Koninklijke Ten Cate		28,545
		Advanced Textiles & Industrial Fabrics
	327,000	OPG Groep		28,405
		Healthcare Supplies & Pharmacies
	574,000	IM Tech		27,709
		Engineering & Technical Services
	439,400	Sligro Food Group		23,327
		Food Service & Wholesaling
	330,000	Smit Internationale		23,216
		Harbor & Offshore Towage & Marine Services
	890,000	Unit 4 Agresso (b)		17,901
		Business & Security Software
				296,750
		>Germany: 7.9%
	900,000	Rhoen-Klinikum		40,082
		Health Care Services
	275,000	Wincor Nixdorf		35,112
		Retail POS Systems & ATM Machines
	2,000,000	Depfa Bank		33,154
		Investment Banker to Public Authorities
	27,500	Porsche		26,536
		Specialty Automobile Manufacturer
	775,000	CTS Eventim (b)		23,763
		Event Ticket Sales
	450,000	Hugo Boss Designs		18,943
		Fashion Apparel
	260,000	Grenkeleasing		17,292
		Financing for IT Equipment
	320,000	Vossloh		16,225
		Rail Infrastructure & Diesel Locomotives
	415,000	GFK		15,128
		Market Research Services
	870,000	Takkt		13,828
		Mail Order Retailer of Office & Warehouse Durables
	100,000	Deutsche Boerse		13,597
		Trading, Clearing, Settlement Services for Financial Markets
	75,000	Rational		12,248
		Commercial Oven Manufacturer
	200,000	Bilfinger Berger		10,856
		Construction & Related Services

1-800-922-6769

Number of Shares			Value (000)
		>Germany—continued
	296,000	Deutsche Beteiligungs	$	6,172
		Private Equity Investment Management
				282,936
		>Ireland: 6.1%
	2,000,000	Bank of Ireland		35,801
		Irish Commercial Bank
	2,000,000	IAWS Group		35,262
		Baked Goods
	2,200,000	Anglo Irish Bank		34,280
		Small Business & Middle Market Banking
	2,350,000	Grafton Group		29,581
		Builders Materials Wholesaling & Do-it-yourself Retailing
	6,856,625	United Drug		29,361
		Irish Pharmaceutical Wholesaler & Outsourcer
	2,500,000	C&C Group		21,712
		Beverage Company
	1,150,000	Kingspan Group		20,078
		Building Insulation & Environmental Containers
	720,000	Paddy Power		12,470
		Irish Betting Services
				218,545
		>Switzerland: 4.9%
	30,000	Geberit		34,662
		Plumbing Supplies
	475,000	Kuehne & Nagel		34,579
		Freight Forwarding/Logistics
	275,000	Synthes		33,132
		Products for Orthopedic Surgery
	24,000	Sika		26,661
		Chemicals for Construction & Industrial Applications
	25,000	Givaudan		19,660
		Fragrances & Flavors
	300,000	Schindler		15,535
		Elevator Manufacturer & Service Provider
	275,000	Logitech (b)		10,602
		Branded Peripheral Computer Devices
	27,000	BKW Energie		2,364
		Electric Utility
				177,195
		>Italy: 3.3%
	9,100,000	Cir Compagnie		25,899
		Italian Holding Company
	2,120,000	Davide Campari		21,961
		Spirits & Wines
	404,000	Banca Italease		20,188
		Italian Leasing & Factoring Leader
	2,000,000	Amplifon		16,999
		Hearing Aid Retailer
	1,223,000	GranitiFiandre		13,163
		Innovative Stoneware
	12,800,000	Ducati Motor (b)		10,867
		Motorcycles & Related Merchandise
	350,000	Sabaf		9,961
		Supplier to White Goods OEMS
				119,038

Number of Shares			Value (000)
		>Sweden: 3.3%
	1,544,998	Hexagon	$	56,245
		Measurement Equipment & Polymers
	2,580,000	Tele2		26,034
		European Mobile Operator & Services Reseller
	755,000	Nobia		24,490
		Kitchen Cabinet Manufacturing & Distribution
	422,000	Sweco		11,541
		Engineering Consultants
				118,310
		>Russia: 1.1%
	775,000	Novolipetsk Steel		16,999
		Vertically Integrated Steel Producer
	575,800	RBC Information Systems (b)		15,202
		Financial Information, Media & IT Services in Russia
	370,000	Mechel Steel Group		8,284
		Coking Coal
				40,485
		>Spain: 0.8%
	620,000	Red Electrica		21,379
		Spanish Power Grid
	120,700	Bankinter		7,768
		Mortgage Lender
				29,147
		>Czech Republic: 0.7%
	183,000	Komercni Banka		26,775
		Leading Czech Universal Bank
		>Greece: 0.7%
	936,000	Intralot		25,045
		Lottery & Gaming Systems/Services
		>Poland: 0.6%
	820,500	Central European Distribution (b)		20,644
		Vodka Production & Alcohol Distribution
		>Finland: 0.5%
	1,756,000	Jaakko Poyry		18,880
		Engineering Consultants
		>Denmark: 0.5%
	280,000	Novozymes		18,872
		Industrial Enzymes
		>Austria: 0.4%
	300,000	Wienerberger		14,255
		Bricks & Clay Roofing Tiles
		Europe: Total		2,130,097
Asia: 21.5%
		>Japan: 15.2%
	546,000	Daito Trust Construction		30,358
		Apartment Builder
	43,500	Jupiter Telecommunications (b)		30,155
		Largest Cable Service Provider in Japan

Columbia Acorn International

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Japan—continued
	3,700,000	Kansai Paint	$	29,606
		Paint Producer in Japan, India, China & Southeast Asia
	1,272,000	Ushio		26,935
		Industrial Light Sources
	718,000	Ito En		26,340
		Bottled Tea & Other Beverages
	868,000	Park 24		25,496
		Parking Lot Operator
	600,000	Aeon Mall		25,180
		Suburban Shopping Mall Developer, Owner & Operator
	453,000	Hogy Medical		23,806
		Disposable Surgical Products
	22,500	Sparx Asset Management		23,516
		Fund Management
	350,000	USS		23,172
		Used Car Auctioneer
	600,000	Hoya		21,450
		Opto-Electrical Components & Eyeglass Lenses
	785,000	JSR		19,922
		Films & Chemicals for LCD Screens & Electronics
	650,000	Shimano		19,922
		Bicycle Components & Fishing Tackle
	2,000,000	Chiba Bank		18,773
		Regional Bank
	4,310	Kenedix		18,665
		Real Estate Investment Management
	220,000	Fast Retailing		17,914
		Apparel Retailer
	710,000	Sato		16,445
		Bar Code Printers & Supplies
	714,000	FCC		14,176
		Auto/Motorcycle Clutches
	965,000	T. Hasegawa		13,774
		Industrial Flavors & Fragrances
	2,248,000	Hiroshima Bank		13,740
		Regional Bank
	918,000	Toyo Technica		12,665
		Value Added Reseller of Imported Instrumentation
	2,960	Risa Partners		11,762
		NPL & Real Estate Related Investment
	1,500,000	Bank of Fukuoka		11,465
		Regional Bank
	960	Osaka Securities Exchange		11,407
		Osaka Securities Exchange
	1,650	Japan Pure Chemical		10,713
		Precious Metal Plating Chemicals for Electronics
	430,000	Yusen Air & Sea Service		10,105
		Airfreight Logistics
	1,230,000	Kamigumi		9,349
		Port Cargo Handling & Logistics
	375,000	Nagaileben		8,438
		Medical/Healthcare Related Clothes
	321,100	Kintetsu World Express		7,623
		Airfreight Logistics
	450,200	Ain Pharmaciez		7,483
		Dispensing Pharmacy/Drugstore Operator
	1,713	Advance Create		4,973
		Independent Insurance Distributor
				545,328

Number of Shares			Value (000)
		>Taiwan: 2.1%
	6,822,000	Advantech	$	19,583
		Embedded Computers
	18,300,000	Phoenixtec Power		18,601
		Uninterruptible Power Supplies
	3,000,000	Novatek Microelectronics		14,451
		LCD Related IC Designer
	7,280,000	Wah Lee Industrial		13,352
		Distributor of Chemicals, Materials, & Equipment
	7,186,000	Springsoft		11,084
		Electronic Design Automation Software
				77,071
		>Hong Kong: 1.5%
	5,000,000	Hong Kong Exchanges and Clearing		32,136
		Hong Kong Equity & Derivatives Market Operator
	14,000,000	Techtronic Industries		18,922
		Power Tools & Motorized Appliances
	10,996,000	Linmark Group		1,731
		Global Sourcing Agent of Consumer Goods
				52,789
		>India: 0.9%
	1,300,000	Housing Development Finance		32,001
		Indian Mortgage Lender
		>South Korea: 0.6%
	250,000	Hyundai Mobis		21,124
		Auto Parts
		>China: 0.5%
	45,000,000	Global Bio-Chem Technology Group		19,028
		Refiner of Corn-based Commodities
		>Indonesia: 0.5%
	15,000,000	Perusahaan Gas Negara		18,192
		Gas Pipeline Operator
		>Singapore: 0.2%
	7,053,000	Comfort Del Gro		6,798
		Taxi & Mass Transit Service
		Asia: Total		772,331
Other Countries: 10.7%
		>Canada: 5.3%
	1,060,000	Alliance Atlantis Communication (b)		31,051
		CATV Channels, TV/Movie Production/Distribution
	1,370,000	Rona (b)		24,607
		Leading Canadian Do-it-yourself Retailer
	400,000	Falconbridge		21,070
		Diversified Mining Holding Company
	1,155,000	Talisman Energy		20,155
		Oil & Gas Producer
	1,190,000	Shawcor		17,685
		Oilfield Services
	6,775,000	UrAsia Energy Legend (b)		16,994
		Uranium Mining in Kazakhstan

1-800-922-6769

Number of Shares			Value (000)
		>Canada—continued
	950,000	Van Houtte (c)	$	15,795
		Coffee Services & Equipment
	530,000	Major Drilling Group (b)		10,597
		Mining Exploration Driller
	2,000,000	Northern Orion Resources (b)		9,818
		Copper & Gold Mining in Argentina
	835,000	Kinross Gold (b)		9,103
		Gold Mining
	850,000	Ivanhoe Mines (b)		5,757
		Copper Mine Project in Mongolia
	2,036,000	RailPower Technologies 144A (b)(c)(d)		4,377
	789,000	RailPower Technologies (c)		1,696
		Hybrid Locomotives
				188,705
		>Australia: 2.9%
	3,000,000	Billabong International		34,250
		Action Sports Apparel Brand Manager
	5,450,000	Sino Gold (b)		20,343
		Gold Mining in The People's Republic of China
	4,000,000	ABC Learning Center		19,036
		Childcare Centers
	350,000	Perpetual Trustees		19,034
		Mutual Fund Management
	2,000,000	Jubilee Mines		11,989
		Nickel Mining in Australia
				104,652
		>South Africa: 1.4%
	180,000	Impala Platinum		33,085
		Platinum Group Metals Mining & Refining
	4,500,000	Edgars Consolidated Stores		18,140
		Leading Retail Conglomerate
				51,225
		>United States: 0.6%
	415,000	Atwood Oceanics (b)		20,584
		Contract Drilling
		>New Zealand: 0.5%
	5,500,000	Sky City Entertainment		18,078
		Casino/Entertainment Complex
		Other Countries: Total		383,244
Latin America: 4.5%
		>Brazil: 2.4%
	2,500,000	Natura Cosmeticos		26,202
		Direct Retailer of Cosmetics
	4,300,000	Suzano		25,273
		Pulp & Paper Producer
	720,000	Porto Seguro (b)		12,300
		Auto & Life Insurance
	392,000	Diagnosticos (b)		7,782
		Medical Diagnostic Services

Number of Shares or Principal Amount			Value (000)
	1,085,000	American Banknote (b)	$	7,013
		Manufacturer of Smart Cards
	293,000	Ultrapar		4,613
		Specialty Chemicals & Liquid Propane Gas Distribution
	170,000	Localiza Rent A Car		3,257
		Car Rental
				86,440
		>Mexico: 1.3%
	4,500,000	Consorcio ARA		18,530
		Affordable Housing Builder
	414,000	Grupo Aeroportuario Del Sureste		13,906
		Cancun/Cozumel Airport Operator
	4,200,000	Urbi Desarrollo (b)		9,740
		Affordable Housing Builder
	100,000	Grupo Aeroportuario Del Pacifia		3,185
		Mexican Airport Operator
				45,361
		>Chile: 0.4%
	160,000	Sociedad Quimica y Minera de Chile (Chile)		16,662
		Producer of Specialty Fertilizers, Lithium, & Iodine
		>Argentina: 0.4%
	350,000	Tenaris		14,172
		Oil, Gas & Industrial Seamless Tubes
		Latin America: Total		162,635
	Total Common Stocks: 95.9% (Cost: $2,361,806)			3,448,307
Short-Term Obligations: 3.4%
$	75,000	Conocophillips 5.30% Due 7/03/06 - 7/05/06		74,966
	45,000	Countrywide Financial Funding 5.30% Due 7/06/06		44,967
	4,181	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/3/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 5/9/09 market value $4,268 (repurchase proceeds: $4,183)		4,181
		(Amortized Cost: $124,114)		124,114
	Total Investments: 99.3% (Cost: $2,485,920)(a)(e)			3,572,421
	Cash and Other Assets Less Liabilities: 0.7%			23,881
	Total Net Assets: 100%		$	3,596,302

Columbia Acorn International

>Statement of Investments (Unaudited), continued

>Notes to Statement of Investments (in thousands)

(a) At June 30, 2006, for federal income tax purposes cost of investments was $2,485,920 and net unrealized appreciation was $1,086,501 consisting of gross unrealized appreciation of $1,184,404 and gross unrealized depreciation of $97,903.

(b) Non-income producing security.

Van Houtte					5.91	%
RailPower Technologies					5.16	%

The aggregate cost and value of these companies at June 30, 2006, was $29,676 and $21,869 respectively. Investments in affiliate companies represent 0.61% of total net assets at June 30, 2006. Investment activity and income amounts relating to affiliates during the six months ended June 30, 2006 were as follows:

Dividend Income	$	58
Net realized gain or loss		—
Change in unrealized gain or loss		(10,121	)
Purchases		18,278
Proceeds from sales		2

(d) Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. At June 30, 2006, this security (in thousands) amounted to $4,377 which represents 0.12% of total net assets.

Additional information on this security is as follows:

Security				Acquisition Dates				Shares				Cost (000)				Value (000)
RailPower Technologies 144A					11/10/05 - 11/18/05				2,036,000			$	9,220			$	4,377

(e) On June 30, 2006, the Fund's total investments were denominated in currencies as follows:

Currency	Value		% of Total Net Assets
Euro	$	1,419,023		39.5	%
Japanese Yen		545,329		15.2
British Pounds		295,353		8.2
Canadian Dollar		188,705		5.2
Other currencies less than 5% of total net assets		1,124,011		31.2
	$	3,572,421		99.3	%

1-800-922-6769

Columbia Acorn International

>Portfolio Diversification

At June 30, 2006, the Fund's portfolio investments as a percent of net assets was diversified as follows:

	Value (000)		Percent
>Industrial Goods/Services
Other Industrial Services	$	167,388		4.6	%
Specialty Chemicals		160,483		4.5
Construction		144,124		4.0
Industrial Materials		117,554		3.3
Conglomerates		97,230		2.7
Machinery		82,867		2.3
Outsourcing & Training Services		69,320		1.9
Electrical Components		46,626		1.3
Steel		31,171		0.9
Industrial Distribution		29,581		0.8
		946,344		26.3
>Consumer Goods/Services
Retail		110,323		3.1
Durables Goods		100,385		2.8
Beverage		85,808		2.4
Other Consumer Services		84,757		2.4
Food		58,589		1.6
Apparels		54,924		1.5
Consumer Goods Distribution		43,816		1.2
Gaming		37,516		1.0
Leisure Products		26,540		0.7
Nondurables		26,202		0.7
Furniture & Textiles		24,490		0.7
Entertainment		23,763		0.7
Casinos		18,078		0.5
Travel		3,257		0.1
		698,448		19.4
>Information
Computer Hardware & Related Equipment		83,898		2.3
Business Information & Marketing Services		62,018		1.7
Financial Processors		45,732		1.3
Semiconductors & Related Equipment		35,900		1.0
Internet Related		32,484		0.9
Satellite Broadcasting		31,338		0.9
Television Programming		31,051		0.9
Cable Television		30,155		0.8
Television Broadcasting		29,764		0.8
Business Software		28,986		0.8
Telephone Services		26,034		0.7
Computer Services		15,201		0.4
Electronics Distribution		13,352		0.4
Instrumentation		12,665		0.4
Publishing		5,485		0.2
		484,063		13.5

	Value (000)		Percent
>Finance
Banks	$	208,157		5.8	%
Other Finance Companies		121,350		3.4
Insurance		54,849		1.5
Money Management		48,722		1.4
Savings & Loans		39,769		1.1
Credit Cards		7,013		0.2
		479,860		13.4
>Energy/Minerals
Mining		149,883		4.2
Oil Services		116,170		3.2
Oil/Gas Producers		65,071		1.8
Refining/Marketing/ Distribution		46,948		1.3
Agricultural Commodities		44,301		1.2
Non-Ferrous Metals		10,597		0.3
		432,970		12.0
>Other Industries
Transportation		82,834		2.3
Real Estate		75,076		2.1
Regulated Utilities		57,594		1.6
		215,504		6.0
>Health Care
Services		68,486		1.9
Medical Equipment		53,244		1.5
Hospital/Laboratory Supplies		40,027		1.1
Pharmaceuticals		29,361		0.8
		191,118		5.3
Total Common Stocks		3,448,307		95.9
Short-Term Obligations		124,114		3.4
Total Investments		3,572,421		99.3
Cash and Other Assets Less Liabilities		23,878		0.7
Total Net Assets	$	3,596,299		100.0	%

Columbia Acorn USA

>Major Portfolio Changes in the Second Quarter (Unaudited)

	Number of Shares
	03/31/06		06/30/06
Additions
Information
Avid Technology		454,900		779,900
Concur Technologies		30,400		230,400
Gemstar-TV Guide International		2,375,653		2,580,000
II VI		435,000		505,000
Kronos		500,650		660,650
Nice Systems (Israel)		456,600		566,600
(includes the effect of a 2 for 1 stock split)
Openwave Systems		0		100,000
Progress Software		118,600		347,000
Saga Communications		98,100		300,000
Time Warner Telecom		786,000		1,086,000
Trimble Navigation		90,000		125,000
ValueClick		285,000		460,000
webMethods		83,500		279,100
Consumer Goods/Services
Carter's		80,200		545,200
(includes the effect of a 2 for 1 stock split)
J Crew Group		0		125,000
Oxford Industries		529,200		634,200
Petco Animal Supplies		428,000		608,000
Red Robin Gourmet Burgers		68,800		163,800
True Religion Apparel		205,000		675,200
Health Care
LCA-Vision		143,995		210,000
PSS World Medical		150,000		380,000
United Surgical Partners		150,000		550,000
Industrial Goods/Services
Goodman Global		0		132,000
Simpson Manufacturing		0		100,000
Other Industries
Highland Hospitality		235,000		350,000
Energy/Minerals
Atwood Oceanics		0		152,000
Finance
Delphi Financial Group		29,000		87,000
(includes the effect of a 3 for 2 stock split)

	Number of Shares
	03/31/06		06/30/06
Sales
Information
CDW		28,000		0
Getty Images		104,800		44,000
Global Payments		423,280		393,280
JDA Software		723,800		524,000
MRO Software		242,000		57,950
Plexus		131,100		105,000
Tellabs		1,610,000		1,525,000
Consumer Goods/Services
Aeropostale		200,000		130,000
Sports Authority		105,000		0
Health Care
Charles River Laboratories		303,000		258,000
Incyte		450,000		0
Neurocrine Biosciences		192,000		0
Energy/Minerals
Chicago Bridge & Iron		585,000		535,000
Newpark Resources		1,001,000		350,900
Pioneer Drilling		266,800		0

1-800-922-6769

Columbia Acorn USA

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares			Value (000)
			Common Stocks: 91.5%
Information: 31.2%
		>Business Software: 8.2%
	779,900	Avid Technology (b)	$	25,994
		Digital Nonlinear Editing Software & Systems
	660,650	Kronos (b)		23,922
		Labor Management Solutions
	455,200	Micros Systems (b)		19,883
		Information Systems for Restaurants & Hotels
	2,100,000	Novell (b)		13,923
		Directory, Operating System & Identity Management Software
	347,000	Progress Software (b)		8,123
		Application Development Software
	405,800	SSA Global Technologies (b)		7,864
		Enterprise Resource Planning Software
	524,000	JDA Software (b)		7,352
		Application/Software & Services for Retailers
	327,200	Parametric Technology (b)		4,159
		Engineering Software & Services
	230,400	Concur Technologies (b)		3,564
		Web Enabled Cost & Expense Management Software
	279,100	webMethods (b)		2,755
		Enterprise Applications Integration Tools
	59,300	Witness Systems (b)		1,196
		Customer Experience Management Software
	57,950	MRO Software (b)		1,163
		Enterprise Maintenance Software
				119,898
		>Mobile Communications: 5.9%
	1,005,000	Crown Castle International (b)		34,713
		Communications Towers
	356,605	Alltel		22,762
		Cellular & Wireline Telephone Services
	506,000	American Tower (b)		15,747
		Communications Towers in USA & Mexico
	1,633,000	Dobson Communications (b)		12,623
		Rural & Small City Cellular Telephone Services
	100,000	Openwave Systems (b)		1,154
		Internet Software for Mobile Devices
				86,999
		>Computer Hardware and Related Equipment: 4.1%
	566,600	Nice Systems (Israel) (b)		15,944
		Audio & Video Recording Solutions
	505,000	II VI (b)		9,242
		Laser Components
	147,800	Amphenol		8,271
		Electronic Connectors
	584,000	Symbol Technologies		6,301
		Mobile Computers & Barcode Scanners
	260,000	Intermec (b)		5,964
		Bar Code & Wireless LAN Systems
	99,000	Zebra Technologies (b)		3,382
		Bar Code Printers
	100,000	Belden CDT		3,305
		Specialty Cable
	424,100	Seachange International (b)		2,952
		Systems for Video On Demand & Ad Insertion

Number of Shares			Value (000)
	40,000	Rogers (b)	$	2,254
		PCB Laminates & High-performance Foams
	90,000	Netgear (b)		1,949
		Networking Products for Small Business & Home
				59,564
		>Telecommunications Equipment: 1.7%
	1,525,000	Tellabs (b)		20,298
		Telecommunications Equipment
	310,000	Andrew (b)		2,746
		Wireless Infrastructure Equipment
	323,500	Symmetricom (b)		2,287
		Network Timing & Synchronization Devices
				25,331
		>Semiconductors and Related Equipment: 1.5%
	1,050,000	Entegris (b)		10,006
		Semiconductor Wafer Shipping & Handling Products
	683,490	Integrated Device Technology (b)		9,692
		Communications Semiconductors
	70,000	Littelfuse (b)		2,407
		Little Fuses
				22,105
		>Financial Processors: 1.3%
	393,280	Global Payments		19,094
		Credit Card Processor
		>Business Information and Marketing Services: 1.2%
	530,000	Ceridian (b)		12,953
		HR Services & Payment Processing
	44,000	Getty Images (b)		2,794
		Photographs for Publications & Electronic Media
	98,300	Navigant Consulting (b)		2,226
		Financial Consulting Firm
				17,973
		>Telephone Services: 1.2%
	1,086,000	Time Warner Telecom (b)		16,127
		Fiber Optic Telephone/Data Service Provider
	50,000	Commonwealth Telephone		1,658
		Rural Phone Franchises & Competing Telco
				17,785
		>Internet Related: 1.0%
	980,000	CNET Networks (b)		7,820
		Internet Advertising on Niche Websites
	460,000	ValueClick (b)		7,061
		Internet Advertising
				14,881
		>Instrumentation: 1.0%
	140,000	Mettler Toledo (b)		8,480
		Laboratory Equipment
	125,000	Trimble Navigation (b)		5,580
		GPS-Based Instruments
				14,060

Columbia Acorn USA

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Radio: 0.9%
	511,100	Salem Communications (b)	$	6,650
		Radio Stations for Religious Programming
	705,500	Spanish Broadcasting System (b)		3,605
		Spanish Language Radio Stations
	300,000	Saga Communications (b)		2,718
		Radio Stations in Small & Mid Sized Cities
				12,973
		>Computer Services: 0.8%
	1,005,500	AnswerThink Consulting (b)		4,052
		IT Integration & Best Practice Research
	786,000	RCM Technologies (b)(c)		3,946
		Technology & Engineering Services
	95,000	SRA International (b)		2,530
		Government IT Services
	235,000	Igate Capital (b)		1,502
		IT & BPO Outsourcing Services
				12,030
		>CATV: 0.8%
	2,580,000	Gemstar-TV Guide International (b)		9,082
		TV Program Guides & CATV Programming
	140,000	Discovery Holding (b)		2,048
		CATV Programming
				11,130
		>TV Broadcasting: 0.7%
	1,125,000	Entravision Communications (b)		9,641
		Spanish Language TV, Radio & Outdoor
	138,500	Gray Television		802
		Mid Market Affiliated TV Stations
				10,443
		>Gaming Equipment: 0.4%
	200,000	Bally Technologies (b)		3,294
		Slot Machines & Software
	98,500	Shuffle Master (b)		3,229
		Card Shufflers & Casino Games
				6,523
		>Television Programming: 0.3%
	460,000	Lions Gate Entertainment (b)		3,933
		Film & TV Studio
		>Contract Manufacturing: 0.2%
	105,000	Plexus (b)		3,592
		Electronic Manufacturing Services
		>Publishing: 0.0%
	13,850	Triple Crown Media (b)		120
		Newspapers, Paging & Collegiate Sports Marketing
		Information: Total		458,434
Consumer Goods/Services: 17.5%
		>Retail: 5.9%
	398,000	Abercrombie & Fitch		22,061
		Teen Apparel Retailer
	486,250	Christopher & Banks		14,101
		Women's Apparel Retailer

Number of Shares			Value (000)
	608,000	Petco Animal Supplies (b)	$	12,421
		Pet Supplies & Services
	224,500	Ann Taylor Stores (b)		9,739
		Women's Apparel Retailer
	353,000	Chico's FAS (b)		9,524
		Women's Specialty Retail
	203,000	Michaels Stores		8,372
		Craft & Hobby Specialty Retailer
	130,000	Aeropostale (b)		3,756
		Mall-Based Teen Retailer
	125,000	J Crew Group (b)		3,431
		Multi-Channel Branded Retailer
	95,000	Genesco (b)		3,218
		Multi-Concept Branded Footwear Retailer
				86,623
		>Apparel: 3.9%
	634,200	Oxford Industries		24,994
		Branded & Private Label Apparel
	545,200	Carter's (b)		14,410
		Children's Branded Apparel
	675,200	True Religion Apparel (b)		11,951
		Premium Denim
	222,200	Coach (b)		6,644
		Designer & Retailer of Branded Leather Accessories
				57,999
		>Other Consumer Services: 2.4%
	416,000	ITT Educational Services (b)		27,377
		Post-secondary Degree Programs
	387,700	Central Parking		6,203
		Owner, Operator, Manager of Parking Lots & Garages
	60,000	Weight Watchers		2,453
		Weight Loss Programs
				36,033
		>Leisure Products: 1.9%
	301,300	International Speedway Motors		13,971
		Largest Motorsports Racetrack Owner & Operator
	195,500	Speedway Motorsports		7,378
		Motorsport Racetrack Owner & Operator
	106,000	Polaris Industries		4,590
		Leisure Vehicles & Related Products
	195,000	Callaway Golf		2,533
		Premium Golf Clubs & Balls
				28,472
		>Nondurables: 1.5%
	496,400	Scotts Miracle-Gro		21,008
		Consumer Lawn & Garden Products
	100,000	Prestige Brands (b)		997
		OTC, Household & Personal Care Products
				22,005
		>Restaurants: 1.0%
	337,500	Sonic (b)		7,017
		Quick Service Restaurant
	163,800	Red Robin Gourmet Burgers (b)		6,971
		Casual Dining Restaurant
				13,988

1-800-922-6769

Number of Shares			Value (000)
		>Furniture and Textiles: 0.6%
	106,000	HNI	$	4,807
		Office Furniture & Fireplaces
	90,000	Herman Miller		2,319
		Office Furniture
	20,000	Mohawk Industries (b)		1,407
		Carpet & Flooring
				8,533
		>Travel: 0.2%
	45,000	Vail Resorts (b)		1,670
		Ski Resort Operator & Developer
	13,200	Kerzner International (Bahamas) (b)		1,046
		Destination Resorts & Casinos
				2,716
		>Other Durable Goods (includes auto related): 0.1%
	40,000	Cavco Industries (b)		1,778
		Higher End Manufactured Homes
		Consumer Goods/Services: Total		258,147
Health Care: 12.6%
		>Health Care Services: 4.3%
	550,000	United Surgical Partners (b)		16,539
		Outpatient Surgery Center
	210,000	LCA-Vision		11,111
		Lasik Surgery Centers
	291,800	Lincare Holdings (b)		11,042
		Home Healthcare Services
	199,875	Coventry Health Care (b)		10,981
		HMO
	258,000	Charles River Laboratories (b)		9,494
		Pharmaceutical Research
	175,000	PRA International (b)		3,897
		Contract Research Organization
				63,064
		>Medical Equipment: 3.8%
	577,400	Edwards Lifesciences (b)		26,231
		Heart Valves
	380,000	PSS World Medical (b)		6,707
		Medical Supplies Distributor
	220,000	Viasys Healthcare (b)		5,632
		Respiratory & Neurology Medical Equipment
	105,000	Vital Signs		5,201
		Anesthesia, Respiratory & Sleep Products
	94,171	Advanced Medical Optics (b)		4,774
		Medical Devices for Eye Care
	165,000	Intermagnetics General (b)		4,452
		MRI Equipment
	104,000	Arrow International		3,418
		Disposable Catheters
				56,415
		>Hospital/Laboratory Supplies: 3.1%
	547,400	Serologicals (b)		17,210
		Blood Collection & Antibody Production
	270,700	ICU Medical (b)		11,434
		Intravenous Therapy Products

Number of Shares			Value (000)
	146,200	Diagnostic Products	$	8,504
		Immunodiagnostic Kits
	158,300	Techne (b)		8,061
		Cytokines, Antibodies, other Reagents for Life Sciences
				45,209
		>Biotechnology/Drug Delivery: 1.4%
	360,000	Nektar Therapeutics (b)		6,602
		Drug Delivery Technologies
	293,000	Intermune (b)		4,820
		Drugs for Hepatitis C, Pulmonary Fibrosis & Cancer
	455,000	Ligand Pharmaceuticals (b)		3,845
		Drugs for Pain, Cancer, Osteoporosis, Diabetes
	235,000	Exelixis (b)		2,362
		Treatments for Cancer & Metabolic Disorders
	235,000	Decode Genetics (b)		1,455
		Drugs for Heart Attack, Asthma & Vascular Disease
	100,000	Momenta Pharmaceuticals (b)		1,271
		Sugar Analysis Technology for Drug Design
	375,000	Locus Discovery, Series D. Pfd. (d)		102
		High Throughput Rational Drug Design
	363,636	Metabolex, Series F (d)		84
		Drugs for Diabetes
				20,541
		Health Care: Total		185,229
Industrial Goods/Services: 11.1%
		>Machinery: 6.5%
	580,300	Esco Technologies (b)		31,017
		Automatic Electric Meter Readers
	673,600	Pentair		23,030
		Pumps, Water Treatment & Tools
	373,600	Nordson		18,373
		Dispensing Systems for Adhesives & Coatings
	319,800	Donaldson		10,832
		Industrial Air Filtration
	110,000	Ametek		5,212
		Aerospace/Industrial Instruments
	189,900	K&F Industries Holdings (b)		3,367
		Aircraft Wheels, Brakes & Fuel Tank Bladders
	132,000	Goodman Global (b)		2,004
		HVAC Equipment Manufacturer
	50,000	Kaydon		1,866
		Specialized Friction & Motion Control Products
				95,701
		>Electrical Components: 1.9%
	376,000	Genlyte Group (b)		27,233
		Commercial Lighting Fixtures
		>Construction: 0.9%
	204,050	Florida Rock Industries		10,135
		Aggregates & Concrete
	100,000	Simpson Manufacturing		3,605
		Wall Joint Maker
				13,740

Columbia Acorn USA

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Specialty Chemicals: 0.5%
	357,500	Spartech	$	8,080
		Plastics Distribution & Compounding
		>Outsourcing Services: 0.5%
	400,000	Quanta Services (b)		6,932
		Electrical & Telecom Construction Services
		>Waste Management: 0.5%
	187,250	Waste Connections (b)		6,816
		Solid Waste Management
		>Industrial Distribution: 0.2%
	113,000	NuCo2 (b)		2,717
		Bulk Co2 Gas Distribution to Restaurants
		>Other Industrial Services: 0.1%
	63,000	UTI Worldwide		1,589
		Global Logistics & Freight Forwarding
		Industrial Goods/Services: Total		162,808
Energy/Minerals: 9.4%
		>Oil Services: 4.9%
	401,700	FMC Technologies (b)		27,099
		Oil & Gas Well Head Manufacturer
	535,000	Chicago Bridge & Iron		12,920
		Engineering & Construction for Petrochemicals & LNG
	311,000	Pride International (b)		9,713
		Offshore Drilling Contractor
	152,000	Atwood Oceanics (b)		7,539
		Contract Drilling
	355,000	Hanover Compressor (b)		6,667
		Natural Gas Compressor Rental & Fabrications
	76,500	Carbo Ceramics		3,758
		Natural Gas Well Stimulants
	155,000	Key Energy Services (b)		2,364
		Well Workover Services
	350,900	Newpark Resources (b)		2,158
		Drilling Fluid Services
	11,000	Helmerich & Payne		663
		Contract Driller
				72,881
		>Oil and Gas Producers: 3.6%
	525,000	Quicksilver Resources (b)		19,325
		Natural Gas & Coal Seam Gas Producer
	282,600	Western Gas Resources		16,914
		Oil & Coal Seam Gas Producer
	208,400	Southwestern Energy (b)		6,494
		Natural Gas Producer
	450,000	Vaalco Energy (b)		4,392
		Oil & Gas Producer
	111,200	Equitable Resources		3,725
		Natural Gas Producer & Utility
	92,000	McMoran Exploration (b)		1,619
		Natural Gas Producer & Developer
				52,469

Number of Shares			Value (000)
		>Other Resources: 0.5%
	242,000	Layne Christensen (b)	$	6,861
		Oil & Gas Producer/Engineering & Construction/Contract Drilling
		>Oil Refining/Marketing/Distribution: 0.4%
	155,000	Atmos Energy		4,326
		Dallas Natural Gas Utility
	50,250	Oneok		1,710
		Natural Gas Distribution, Pipeline, Processing & Trading
				6,036
		Energy/Minerals: Total		138,247
Finance: 7.5%
		>Finance Companies: 3.4%
	1,121,500	AmeriCredit (b)		31,312
		Auto Lending
	520,200	World Acceptance (b)		18,478
		Personal Loans
				49,790
		>Insurance: 2.4%
	664,500	HCC Insurance Holdings		19,563
		Specialty Insurance
	14,000	Markel (b)		4,858
		Specialty Insurance
	105,000	Philadelphia Consolidated Holding (b)		3,188
		Specialty Insurance
	87,000	Delphi Financial Group		3,163
		Group Employee Benefit Products & Services
	75,000	Endurance Specialty Holdings		2,400
		Commercial Lines Insurance/Reinsurance
	91,000	United America Indemnity (b)		1,896
		Specialty Insurance
	1,600	Eastern Insurance Holdings (b)		20
		Workers Comp & Specialty Insurance
				35,088
		>Banks: 1.4%
	239,500	TCF Financial		6,335
		Great Lakes Bank
	212,756	Chittenden		5,500
		Vermont & Western Massachusetts Banks
	145,000	Greene County Bancshares		4,489
		Tennessee Bank
	94,000	Associated Banc-Corp		2,964
		Midwest Bank
	20,000	First Financial Bankshares		731
		West Texas Bank
	30,000	West Bancorporation		560
		Des Moines Commercial Bank
				20,579
		>Savings and Loans: 0.3%
	141,400	Anchor Bancorp Wisconsin		4,266
		Wisconsin Thrift
		Finance: Total		109,723

1-800-922-6769

Number of Shares or Principal Amount			Value (000)
Other Industries: 2.2%
		>Real Estate: 1.6%
	560,000	DiamondRock Hospitality	$	8,293
		Hotel Owner
	350,000	Highland Hospitality		4,928
		Hotel Owner
	77,500	Gaylord Entertainment (b)		3,382
		Convention Hotels
	150,000	Kite Realty Group		2,339
		Community Shopping Centers
	90,000	American Campus Communities		2,237
		Student Housing
	110,500	Crescent Real Estate Equities		2,051
		Class 'A' Office Buildings
				23,230
		>Transportation/Regulated Utilities: 0.6%
	424,720	Heartland Express		7,598
		Regional Trucker
	97,500	Northeast Utilities		2,015
		Utility
				9,613
	Other Industries: Total			32,843
	Total Common Stocks: 91.5%	(Cost: $963,933)		1,345,431
Short-Term Obligations: 8.6%
$	65,000	Conocophillips 5.30% Due 7/03/06 - 7/06/06		64,965
	32,000	Countrywide Financial Funding 5.30% Due 7/03/06		31,972
	26,000	Verizon Global Funding 5.30% Due 7/05/06		25,985
	2,797	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/3/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 5/22/08 market value $2,855 (repurchase proceeds: $2,798)		2,797
		(Amortized Cost: $125,719)		125,719
	Total Investments: 100.1% (Cost: $1,089,652)(a)			1,471,150
	Cash and Other Assets Less Liabilities: (0.1%)			(817	)
	Total Net Assets: 100%		$	1,470,333

Columbia Acorn USA

>Statement of Investments (Unaudited), continued

>Notes to Statement of Investments (in thousands)

(a) At June 30, 2006, for federal income tax purposes cost of investments was $1,089,652 and net unrealized appreciation was $381,498 consisting of gross unrealized appreciation of $445,543 and gross unrealized depreciation of $64,045.

(b) Non-income producing security.

RCM Technologies

6.67

The aggregate cost and value of this company at June 30, 2006, was $5,636 and $3,946 respectively. Investments in affiliate companies represent 0.27% of total net assets at June 30, 2006. Investment activity and income amounts relating to affiliates during the six months ended June 30, 2006 were as follows:

Dividend Income	$	—
Net realized gain or loss		—
Change in unrealized gain or loss		(63	)
Purchases		—
Proceeds from sales		—

(d) Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued in good faith by the Board of Trustees. At June 30, 2006, these securities (in thousands) amounted to $186 which represents 0.01% of total net assets.

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost (000)		Value (000)
Locus Discovery, Series D, Pfd.	09/05/01		375,000	$	1,500	$	102
Metabolex, Series F	05/11/00		363,636		2,000		84
				$	3,500	$	186

1-800-922-6769

Columbia Acorn International Select

>Major Portfolio Changes in the Second Quarter (Unaudited)

	Number of Shares
	03/31/06		06/30/06
Additions
Europe
>Ireland
Anglo Irish Bank		174,000		265,000
Bank of Ireland		245,000		280,000
C&C Group		170,000		500,000
>Switzerland
Synthes		25,000		30,000
>Germany
Depfa Bank		185,000		215,000
>Sweden
Hexagon		0		32,000
Tele2		160,000		255,000
>Czech Republic
Komercni Banka		10,300		15,300
>Netherlands
USG People		0		17,000
Asia
>Japan
Hoya		90,000		110,000
Kansai Paint		80,000		280,000
Other Countries
>Canada
Alliance Atlantis Communication		0		72,000
Potash		30,700		35,000
>United States
Atwood Oceanics		0		60,800

	Number of Shares
	03/31/06		06/30/06
Sales
Europe
>Switzerland
BKW Energie		12,100		2,500
>Sweden
Gambro		320,200		0
>Norway
Orkla		47,000		0
Asia
>Japan
Ito En		76,000		36,000
Shimano		130,000		5,600
Ushio		145,000		85,000
Other Countries
>Canada
Kinross Gold		311,000		111,000
Talisman Energy		78,000		0
(includes the effect of a 3 for 1 stock split)
Latin America
>Argentina
Tenaris		29,500		0
(includes the effect of a 5 for 1 stock split)

Columbia Acorn International Select

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares			Value (000)
		Common Stocks: 93.6%
Europe: 55.0%
		>Ireland: 15.9%
	280,000	Bank of Ireland	$	5,012
		Irish Commercial Bank
	500,000	C&C Group		4,342
		Beverage Company
	265,000	Anglo Irish Bank		4,129
		Small Business & Middle Market Banking
	220,000	IAWS Group		3,879
		Baked Goods
	125,000	Grafton Group		1,574
		Builders Materials Wholesaling & Do-it-yourself Retailing
				18,936
		>Switzerland: 10.6%
	30,000	Synthes		3,614
		Products for Orthopedic Surgery
	42,500	Kuehne & Nagel		3,094
		Freight Forwarding/Logistics
	2,400	Geberit		2,773
		Plumbing Supplies
	10,250	Swatch Group		1,729
		Watch & Electronics Manufacturer
	23,000	Schindler		1,191
		Elevator Manufacturer & Service Provider
	2,500	BKW Energie		219
		Electric Utility
				12,620
		>France: 7.4%
	24,200	Neopost		2,755
		Postage Meter Machines
	182,300	SES Global		2,597
		Satellite Broadcasting Services
	20,000	Essilor International		2,011
		Eyeglass Lenses
	18,000	Imerys		1,438
		Industrial Minerals Producer
				8,801
		>Germany: 6.4%
	215,000	Depfa Bank		3,564
		Investment Banker to Public Authorities
	3,300	Porsche		3,184
		Specialty Automobile Manufacturer
	6,000	Deutsche Boerse		816
		Trading, Clearing, Settlement Services for Financial Markets
				7,564
		>United Kingdom: 3.3%
	215,000	Northern Rock		3,971
		Lowest Cost Mortgage Bank in UK
		>Sweden: 3.1%
	255,000	Tele2		2,573
		European Mobile Operator & Services Reseller
	32,000	Hexagon		1,165
		Measurement Equipment & Polymers
				3,738

Number of Shares			Value (000)
		>Denmark: 2.8%
	50,000	Novozymes	$	3,370
		Industrial Enzymes
		>Spain: 2.5%
	88,000	Red Electrica		3,034
		Spanish Power Grid
		>Czech Republic: 1.9%
	15,300	Komercni Banka		2,239
		Leading Czech Universal Bank
		>Netherlands: 1.1%
	17,000	USG People		1,301
		Temporary Staffing Services
		Europe: Total		65,574
Asia: 28.2%
		>Japan: 24.1%
	76,000	Daito Trust Construction		4,226
		Apartment Builder
	110,000	Hoya		3,932
		Opto-Electrical Components & Eyeglass Lenses
	5,299	Jupiter Telecommunications (b)		3,673
		Largest Cable Service Provider in Japan
	55,000	Aeon Mall		2,308
		Suburban Shopping Mall Developer, Owner & Operator
	280,000	Kansai Paint		2,240
		Paint Producer in Japan, India, China & Southeast Asia
	85,000	JSR		2,157
		Films & Chemicals for LCD Screens & Electronics
	30,000	USS		1,986
		Used Car Auctioneer
	1,800	Sparx Asset Management		1,881
		Fund Management
	420	Kenedix		1,819
		Real Estate Investment Management
	85,000	Ushio		1,800
		Industrial Light Sources
	36,000	Ito En		1,321
		Bottled Tea & Other Beverages
	199,800	Hiroshima Bank		1,222
		Regional Bank
	5,600	Shimano		172
		Bicycle Components & Fishing Tackle
				28,737
		>Hong Kong: 3.3%
	610,000	Hong Kong Exchanges and Clearing		3,920
		Hong Kong Equity & Derivatives Market Operator

1-800-922-6769

Number of Shares or Principal Amount			Value (000)
		>Singapore: 0.8%
	1,000,000	Comfort Del Gro	$	964
		Taxi & Mass Transit Service
		Asia: Total		33,621
Other Countries: 10.4%
		>Canada: 6.8%
	35,000	Potash		3,009
		World's Largest Producer of Potash
	72,000	Alliance Atlantis Communication (b)		2,109
		CATV Channels, TV/Movie Production/Distribution
	100,000	Rona (b)		1,796
		Leading Canadian DIY Retailer
	111,000	Kinross Gold (b)		1,210
		Gold Mining
				8,124
		>United States: 2.6%
	60,800	Atwood Oceanics (b)		3,016
		Contract Drilling
		>South Africa: 1.0%
	6,500	Impala Platinum Holdings		1,195
		Platinum Group Metals Mining & Refining
		Other Countries: Total		12,335
		Total Common Stocks: 93.6% (Cost: $90,604)		111,530
Short-Term Obligation: 6.2%
$	7,418	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/03/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 5/22/08 market value $7,570 (repurchase proceeds: $7,421)		7,418
		(Amortized Cost: $7,418)
	Total Investments: 99.8% (Cost: $98,022)(a)(c)			118,948
	Cash and Other Assets Less Liabilities: 0.2%			230
	Total Net Assets: 100%		$	119,178

Columbia Acorn International Select

>Statement of Investments (Unaudited), continued

>Notes to Statement of Investments (in thousands)

(a) At June 30, 2006, for federal income tax purposes cost of investments was $98,022 and net unrealized appreciation was $20,926 consisting of gross unrealized appreciation of $24,229 and gross unrealized depreciation of $3,303.

(b) Non-income producing security.

Currency	Value		% of Total Net Assets
Euro	$	39,637		33.3	%
Japanese Yen		28,737		24.1
US Dollar		13,443		11.3
Swiss Franc		12,620		10.6
Other currencies less than 5% of total net assets		24,511		20.5
	$	118,948		99.8	%

1-800-922-6769

Columbia Acorn International Select

>Portfolio Diversification

At June 30, 2006, the Fund's portfolio investments as a percent of net assets was diversified as follows:

	Value (000)		Percent
>Industrial Goods/Services
Specialty Chemicals	$	7,768		6.5	%
Construction		6,999		5.9
Other Industrial Services		4,285		3.6
Machinery		2,755		2.3
Electrical Components		1,800		1.5
Industrial Distribution		1,573		1.3
Industrial Materials		1,438		1.2
Outsourcing Services		1,301		1.1
Conglomerates		1,165		1.0
		29,084		24.4
>Finance
Banks		20,136		16.9
Money Management		1,881		1.6
		22,017		18.5
>Consumer Goods/Services
Beverage		5,663		4.8
Durables Goods		5,085		4.3
Retail		4,104		3.4
Food		3,879		3.2
Consumer Goods Distribution		1,986		1.7
		20,717		17.4
>Information
Financial Processors		4,736		4.0
Semiconductors & Related Equipment		3,933		3.3
Cable Television		3,673		3.1
Satellite Broadcasting		2,597		2.2
Telephone Services		2,573		2.1
Television Programming		2,109		1.7
		19,621		16.4

	Value (000)		Percent
>Energy/Minerals
Mining	$	5,414		4.6	%
Oil/Gas Producers		3,015		2.5
		8,429		7.1
>Other Industries
Regulated Utilities		3,253		2.8
Real Estate		1,819		1.5
Transportation		964		0.8
		6,036		5.1
>Health Care
Medical Equipment		5,626		4.7
		5,626		4.7
Total Common Stocks		111,530		93.6
Short-Term Obligation		7,418		6.2
Total Investments		118,948		99.8
Cash and Other Assets Less Liabilities		230		0.2
Total Net Assets	$	119,178		100.0	%

Columbia Acorn Select

>Major Portfolio Changes in the Second Quarter (Unaudited)

	Number of Shares
	03/31/06		06/30/06
Additions
Consumer Goods/Services
Coach		1,400,000		1,506,000
Expedia		1,200,000		3,300,000
Petco Animal Supplies		1,300,000		1,350,000
Information
Avid Technology		1,600,000		1,650,000
Liberty Global, Series A		1,000,000		1,139,734
Novell		5,000,000		5,500,000
Sanmina-SCI		0		4,000,000
Tellabs		9,600,000		9,750,000
Industrial Goods/Services
Worthington Industries		2,150,000		2,250,000
Energy/Minerals
Potash (Canada)		400,000		480,000
UrAsia Energy (Canada)		1,900,000		2,800,000
Finance
Janus Capital Group		2,500,000		3,200,000

	Number of Shares
	03/31/06		06/30/06
Sales
Information
IAC/Interactive Corp		544,000		0
Liberty Global, Series C		3,400,000		3,232,702
Tektronix		1,400,000		0
Tribune Company		803,700		702,900
Finance
Associated Banc-Corp		750,000		0
Health Care
Coventry Health Care		900,000		0

1-800-922-6769

Columbia Acorn Select

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares			Value (000)
		Common Stocks: 94.6%
Consumer Goods/Services: 29.4%
		>Consumer Services: 11.8%
	1,625,000	ITT Educational Services (b)	$	106,941
		Post-secondary Degree Programs
	3,500,000	Safeway		91,000
		Supermarkets
	728,000	Weight Watchers		29,768
		Weight Loss Programs
				227,709
		>Retail: 7.9%
	1,400,000	Abercrombie & Fitch		77,602
		Teen Apparel Retailer
	845,000	Costco Wholesale		48,275
		Warehouse Superstores
	1,350,000	Petco Animal Supplies (b)		27,580
		Pet Supplies & Services
				153,457
		>Leisure Products: 4.9%
	1,100,000	Harley-Davidson		60,379
		Motorcycles & Related Merchandise
	740,000	International Speedway Motors		34,314
		Largest Motorsports Racetrack Owner & Operator
				94,693
		>Travel: 2.5%
	3,300,000	Expedia (b)		49,401
		Online Travel Services Company
		>Apparel: 2.3%
	1,506,000	Coach (b)		45,029
		Designer & Retailer of Branded Leather Accessories
		Consumer Goods/Services: Total		570,289
Information: 29.0%
		>Telecommunications Equipment: 6.7%
	9,750,000	Tellabs (b)		129,773
		Telecommunications Equipment
		>CATV: 6.6%
	3,232,702	Liberty Global, Series C (b)		66,497
	1,139,734	Liberty Global, Series A (b)		24,504
		CATV Holding Company
	2,500,000	Discovery Holding (b)		36,575
		CATV Programming
				127,576
		>Business Software: 4.7%
	1,650,000	Avid Technology (b)		54,995
		Digital Nonlinear Editing Software & Systems
	5,500,000	Novell (b)		36,465
		Directory, Operating System & Identity Management Software
				91,460
		>Mobile Communications: 3.7%
	2,300,000	American Tower (b)		71,575
		Communications Towers in USA & Mexico

Number of Shares			Value (000)
		>Internet Related: 3.0%
	9,600,000	Skillsoft Publishing (b)(c)	$	58,752
		Web-based Learning Solutions (E-Learning)
		>Financial Processors: 1.8%
	729,500	SEI Investments		35,658
		Mutual Fund Administration & Investment Management
		>Publishing: 1.2%
	702,900	Tribune Company		22,795
		Newspapers & TV Stations
		>Contract Manufacturing: 1.0%
	4,000,000	Sanmina-SCI (b)		18,400
		Backplane & Electronic Manufacturing Services
		>Computer Services: 0.3%
	1,367,000	AnswerThink Consulting (b)		5,509
		IT Integration & Best Practice Research
		Information: Total		561,498
Industrial Goods/Services: 13.7%
		>Other Industrial Services: 3.8%
	1,322,000	Expeditors International of Washington		74,045
		International Freight Forwarder
		>Outsourcing Services: 2.7%
	3,030,000	Quanta Services (b)		52,510
		Electrical & Telecom Construction Services
		>Steel: 2.5%
	2,250,000	Worthington Industries		47,138
		Steel Processing
		>Waste Management: 2.4%
	1,300,000	Waste Management		46,644
		U.S. Garbage Collection & Disposal
		>Industrial Materials: 2.3%
	1,125,000	Mine Safety Appliances		45,225
		Safety Equipment
		Industrial Goods/Services: Total		265,562
Energy/Minerals: 11.4%
		>Mining: 6.2%
	31,500,000	UrAsia Energy (Canada) (b)(c)		79,011
		Uranium Mining in Kazakhstan
	480,000	Potash (Canada)		41,266
		World's Largest Producer of Potash
				120,277

Columbia Acorn Select

>Statement of Investments (Unaudited), continued

Number of Shares or Principal Amount			Value (000)
		>Oil Services: 5.2%
	1,950,000	Pride International (b)	$	60,899
		Contract Drilling
	600,000	FMC Technologies (b)		40,475
		Oil & Gas Well Head Manufacturer
				101,374
		Energy/Minerals: Total		221,651
Finance: 9.3%
		>Money Management: 5.2%
	3,200,000	Janus Capital Group		57,280
		Manages Mutual Funds
	975,000	Nuveen Investments		41,974
		Specialty Mutual Funds
				99,254
		>Insurance: 4.1%
	1,800,000	Conseco (b)		41,580
		Life, Long Term Care & Medical Supplement Insurance
	112,000	Markel (b)		38,865
		Specialty Insurance
				80,445
		Finance: Total		179,699
Health Care: 1.8%
		>Health Care Services: 1.8%
	910,000	Lincare Holdings (b)		34,434
		Home Health Care Services
		Health Care: Total		34,434
		Total Common Stock: 94.6% (Cost: $1,388,372)		1,833,133
Short-Term Obligations: 3.2%
$	30,000	Conocophillips 5.30% Due 7/03/06		29,987
	27,000	Countrywide Financial Funding 5.25% Due 7/05/06		26,976
	8,784	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/3/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 5/22/08 market value $4,880 (repurchase proceeds: $4,786)		4,784
		(Amortized Cost: $61,747)		61,747
	Total Investments: 97.8% (Cost: $1,450,119)(a)			1,894,880
	Cash and Other Assets Less Liabilities: 2.2%			42,833
	Total Net Assets: 100%		$	1,937,713

1-800-922-6769

>Notes to Statement of Investments (in thousands)

(a) At June 30, 2006, for federal income tax purposes cost of investments was $1,450,119 and net unrealized appreciation was $444,761 consisting of gross unrealized appreciation of $484,626 and gross unrealized depreciation of $39,865.

(b) Non-income producing security.

Skillsoft Publishing					8.88	%
UrAsia Energy (Canada)					6.56	%

The aggregate cost and value of these companies at June 30, 2006, was $110,886 and $137,763 respectively. Investments in affiliate companies represent 7.11% of total net assets at June 30, 2006. Investment activity and income amounts relating to affiliates during the six months ended June 30, 2006, were as follows:

Dividend Income	$	—
Net realized gain or loss		—
Change in unrealized gain or loss		24,788
Purchases		6,039
Proceeds from sales		—

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1-800-922-6769

Columbia Acorn Family of Funds

> Statements of Assets and Liabilities

> Statements of Operations

> Statements of Changes in Net Assets

> Financial Highlights

> Notes to Financial Statements

Columbia Acorn Family of Funds

>Statements of Assets and Liabilities (Unaudited)

June 30, 2006	Columbia Acorn Fund			Columbia Acorn International		Columbia Acorn USA			Columbia Acorn International Select			Columbia Acorn Select
(in thousands)
Assets:
Unaffiliated investments, at cost	$	9,452,305		$	2,456,244	$	1,084,016		$	98,022		$	1,339,233
Affiliated investments, at cost (See Note 4)		1,819,627			29,676		5,636			—			110,886
Unaffiliated investments, at value	$	14,993,693		$	3,550,552	$	1,467,204		$	118,948		$	1,757,117
Affiliated investments, at value (See Note 4)		2,934,084			21,869		3,946			—			137,763
Cash		2,056			1		13			1			1
Foreign currency (cost: Columbia Acorn Fund $5,941; Columbia Acorn International $5,019; Columbia Acorn International Select $200; Columbia Acorn Select $*)		6,049			5,077		—			203			—	*
Receivable for:
Investments sold		28,918			8,075		1,587			343			45,986
Fund shares sold		24,568			8,551		2,822			117			2,178
Dividends and interest		8,609			6,066		400			197			342
Foreign tax reclaims		793			1,042		2			36			—
Deferred Trustees' Compensation Investments		1,927			538		136			—			—
Other assets		—			122		90			2			—
Total Assets		18,000,697			3,601,893		1,476,200			119,847			1,943,387
Liabilities:
Payable for:
Investments purchased		53,778			711		3,405			384			76
Fund shares redeemed		14,600			1,357		978			97			3,377
Management fee		9,220			2,220		1,024			90			1,270
Administration fee		588			117		48			4			64
12b-1 Service & Distribution fees		2,923			157		132			11			442
Reports to shareholders		633			205		90			36			230
Deferred Trustees' fees		1,927			538		136			12			47
Transfer agent fees		600			80		36			6			135
Trustees' fees		4			—		—			—	*		6
Audit fee		32			34		18			19			18
Custody fees		210			172		—			10			—
Other liabilities		106			—		—			—			9
Total Liabilities		84,621			5,591		5,867			669			5,674
Net Assets	$	17,916,076		$	3,596,302	$	1,470,333		$	119,178		$	1,937,713
Composition of Net Assets:
Paid in capital	$	10,598,812		$	2,229,793	$	1,096,188		$	111,933		$	1,468,574
Undistributed (overdistributed) net investment income (Accumulated net investment loss)		(6,560	)		4,339		(1,371	)		(357	)		(15,027	)
Accumulated net realized gain (loss)		667,823			275,512		(6,049	)		(13,330	)		39,405
Net unrealized appreciation (depreciation) on:
Investments		6,655,845			1,086,501		381,498			20,926			444,761
Foreign currency translations		156			157		67			6			—	*
Net Assets	$	17,916,076		$	3,596,302	$	1,470,333		$	119,178		$	1,937,713
Net asset value per share – Class A (a)	$	28.81		$	37.33	$	26.96		$	22.95		$	23.55
(Net assets/shares)		($3,808,423/132,182)			($211,021/5,652)		($220,043/8,162)			($14,167/617)			($788,153/33,464)
Maximum offering price per share – Class A (b)	$	30.57		$	39.61	$	28.60		$	24.35		$	24.99
(Net asset value per share/front-end sales charge)		($28.81/0.9425)			($37.33/0.9425)		($26.96/0.9425)			($22.95/0.9425)			($23.55/0.9425)
Net asset value and offering price per share – Class B (a)	$	27.71		$	36.65	$	25.95		$	22.24		$	22.69
(Net assets/shares)		($1,406,504/50,764)			($82,345/2,247)		($67,649/2,607)			($7,910/356)			($203,596/8,973)
Net asset value and offering price per share – Class C (a)	$	27.66		$	36.61	$	25.92		$	22.23		$	22.66
(Net assets/shares)		($1,300,779/47,032)			($76,524/2,091)		($50,799/1,960)			($5,006/225)			($155,134/6,847)
Net asset value and offering price per share – Class Z (c)	$	29.49		$	37.58	$	27.52		$	23.16		$	23.87
(Net assets/shares)		($11,400,370/386,621)			($3,226,412/85,846)		($1,131,842/41,121)			($92,095/3,976)			($790,830/33,124)

(a) Redemption price per share is equal to net asset value less any applicable contingent deferred sales charge.

(b) On sales of $50,000 or more the offering price is reduced.

* Rounds to less than $500.

See accompanying notes to financial statements.

1-800-922-6769

Columbia Acorn Family of Funds

>Statements of Operations
For the Six Months Ended June 30, 2006 (Unaudited)

(in thousands)	Columbia Acorn Fund			Columbia Acorn International			Columbia Acorn USA			Columbia Acorn International Select			Columbia Acorn Select
Investment Income:
Dividend income	$	72,878		$	39,687		$	3,023		$	1,249		$	5,670
Dividend income from affiliates (See Note 4)		13,299			58			—			—			—
Interest income		28,493			6,484			3,409			100			1,399
		114,670			46,229			6,432			1,349			7,069
Foreign taxes withheld		(2,712	)		(3,643	)		(5	)		(105	)		(16	)
Total Investment Income		111,958			42,586			6,427			1,244			7,053
Expenses:
Management fee		57,105			13,306			6,073			521			7,840
Administration fee		3,643			701			287			23			391
12b-1 Service and Distribution fees:
Class A		4,680			241			250			15			984
Class B		6,192			355			307			32			890
Class C		6,533			335			235			23			780
Transfer agent fees:
Class A		1,007			69			57			8			326
Class B		1,048			74			59			10			211
Class C		596			33			25			4			111
Class Z		1,265			538			122			28			234
Custody fees		922			919			20			27			29
Trustees' fees		303			47			21			1			15
Registration & blue sky fees		167			128			76			42			106
Reports to shareholders		1,248			320			134			43			308
Compliance fees		259			48			20			2			27
Non-recurring costs (See Note 9)		84			16			7			1			9
Other expenses		364			87			43			30			52
Total expenses		85,416			17,217			7,736			810			12,313
Less custody fees paid indirectly		(60	)		(8	)		(2	)		—	*		(4	)
Less reimbursement of expenses by Investment Adviser		—			—			—			(2	)		—
Less fees waived by Transfer Agent		(817	)		(96	)		(48	)		(7	)		(170	)
Non-recurring costs reimbursed (See Note 9)		(84	)		(16	)		(7	)		(1	)		(9	)
Net Expenses		84,455			17,097			7,679			800			12,130
Net Investment Income (Loss)		27,503			25,489			(1,252	)		444			(5,077	)
Net Realized and Unrealized Gain (Loss) on Portfolio Positions:
Net realized gain (loss) on:
Unaffiliated investments		670,179			276,747			(3,184	)		12,297			39,660
Foreign currency transactions		265			(410	)		—			(18	)		13
Net realized gain (loss)		670,444			276,337			(3,184	)		12,279			39,673
Net change in net unrealized appreciation (depreciation) on:
Unaffiliated investments		(23,305	)		121,881			25,365			(378	)		35,008
Affiliated investments (See Note 4)		253,598			(10,121	)		(63	)		—			24,788
Foreign currency translations		126			14			67			7			—
Foreign capital gains tax		—			3			—			—			—
Net change in unrealized appreciation (depreciation)		230,419			111,777			25,369			(371	)		59,796
Net realized and unrealized gain		900,863			388,114			22,185			11,908			99,469
Net Increase in Net Assets resulting from Operations	$	928,366		$	413,603		$	20,933		$	12,352		$	94,392

* Rounds to less than $500.

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

>Statements of Changes in Net Assets

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA						Columbia Acorn International Select						Columbia Acorn Select
Increase (Decrease) in Net Assets	(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,
(in thousands)	2006			2005			2006			2005			2006			2005			2006			2005			2006			2005
Operations:
Net investment income (loss)	$	27,503		$	49,723		$	25,489		$	24,670		$	(1,252	)	$	1,300		$	444		$	431		$	(5,077	)	$	(7,333	)
Net realized gain (loss) on investments and foreign currency transactions		670,444			890,559			276,337			203,167			(3,184	)		49,825			12,279			5,496			39,673			46,214
Net change in net unrealized appreciation (depreciation) on investments and foreign currency translations and foreign capital gains tax		230,419			898,946			111,777			258,860			25,369			75,612			(371	)		5,773			59,796			140,962
Net Increase from Operations		928,366			1,839,228			413,603			486,697			20,933			126,737			12,352			11,700			94,392			179,843
Distributions Declared to Shareholders From:
Net investment income – Class A		—			(8,157	)		(1	)		(1,772	)		—			—			(2	)		(79	)		(788	)		—
Net realized gain – Class A		(40,975	)		(177,617	)		(3,315	)		(4,275	)		(819	)		(7,747	)		—			—			(2,891	)		(19,098	)
Net investment income – Class B		—			—			—	*		(280	)		—			—			—			(46	)		—			—
Net realized gain – Class B		(15,915	)		(81,483	)		(1,276	)		(2,334	)		(270	)		(3,824	)		—			—			(780	)		(5,029	)
Net investment income – Class C		—			—			(1	)		(171	)		—			—			—	*		(24	)		—			—
Net realized gain – Class C		(14,668	)		(68,235	)		(1,189	)		(1,462	)		(194	)		(2,282	)		—			—			(593	)		(3,559	)
Net investment income – Class Z		—			(52,311	)		(6,544	)		(51,974	)		—			(1,613	)		(196	)		(888	)		(1,614	)		—
Net realized gain – Class Z		(120,087	)		(547,733	)		(46,561	)		(81,064	)		(4,177	)		(43,227	)		—			—			(2,827	)		(19,071	)
Total Distribution to Shareholders		(191,645	)		(935,536	)		(58,887	)		(143,332	)		(5,460	)		(58,693	)		(198	)		(1,037	)		(9,493	)		(46,757	)
Share Transactions:
Subscriptions – Class A		659,206			912,797			88,963			66,630			72,214			66,241			4,045			5,743			88,593			296,611
Distributions reinvested – Class A		37,164			167,704			2,797			4,900			723			6,880			2			71			3,419			17,770
Redemptions – Class A		(385,545	)		(579,536	)		(38,125	)		(14,669	)		(23,405	)		(25,265	)		(1,414	)		(1,004	)		(83,751	)		(143,717	)
Net Increase – Class A		310,825			500,965			53,635			56,861			49,532			47,856			2,633			4,810			8,261			170,664
Subscriptions – Class B		16,838			49,025			10,985			17,173			850			4,001			1,272			2,123			3,191			28,258
Distributions reinvested – Class B		14,515			74,120			1,143			2,310			248			3,491			—			41			697			4,510
Redemptions – Class B		(107,477	)		(174,945	)		(11,978	)		(10,198	)		(7,678	)		(11,124	)		(775	)		(1,480	)		(16,156	)		(26,292	)
Net Increase (Decrease) – Class B		(76,124	)		(51,800	)		150			9,285			(6,580	)		(3,632	)		497			684			(12,268	)		6,476
Subscriptions – Class C		105,355			171,533			33,664			15,891			12,391			8,047			950			1,655			11,122			48,457
Distributions reinvested – Class C		11,709			54,677			890			1,302			163			1,878			—	*		20			483			2,903
Redemptions – Class C		(85,492	)		(149,119	)		(10,292	)		(6,051	)		(4,935	)		(9,090	)		(522	)		(599	)		(12,280	)		(23,251	)
Net Increase (Decrease) – Class C		31,572			77,091			24,262			11,142			7,619			835			428			1,076			(675	)		28,109
Subscriptions – Class Z		1,068,234			1,686,601			403,326			577,455			262,241			302,588			12,943			25,890			135,599			333,604
Distributions reinvested – Class Z		103,086			513,385			39,291			103,732			3,812			40,433			99			582			3,108			13,462
Redemptions – Class Z		(649,562	)		(1,080,069	)		(171,762	)		(284,340	)		(83,258	)		(105,312	)		(4,579	)		(7,003	)		(68,526	)		(155,173	)
Net Increase – Class Z		521,758			1,119,917			270,855			396,847			182,795			237,709			8,463			19,469			70,181			191,893
Net Increase from Share Transactions		788,031			1,646,173			348,902			474,135			233,366			282,768			12,021			26,039			65,499			397,142
Redemption Fees		—			—			107			65			—			—			4			9			—			—
Total Increase in Net Assets		1,524,752			2,549,865			703,725			817,565			248,839			350,812			24,179			36,711			150,398			530,228
Net Assets:
Beginning of period		16,391,324			13,841,459			2,892,577			2,075,012			1,221,494			870,682			94,999			58,288			1,787,315			1,257,087
End of period	$	17,916,076		$	16,391,324		$	3,596,302		$	2,892,577		$	1,470,333		$	1,221,494		$	119,178		$	94,999		$	1,937,713		$	1,787,315
Undistributed (Overdistributed) Net Investment Income or (Accumulated Net Investment Loss)	$	(6,560	)	$	(34,063	)	$	4,339		$	(14,604	)	$	(1,371	)	$	(119	)	$	(357	)	$	(603	)	$	(15,027	)	$	(7,548	)

* Rounds to less than $500.

See accompanying notes to financial statements.

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Columbia Acorn Family of Funds

>Statements of Changes in Net Assets, continued

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA						Columbia Acorn International Select						Columbia Acorn Select
Changes in Shares of Beneficial Interest:	(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,
(in thousands)	2006			2005			2006			2005			2006			2005			2006			2005			2006			2005
Subscriptions – Class A		22,554			34,302			2,347			2,150			2,619			2,559			178			307			3,735			14,487
Shares issued in reinvestment and capital gains – Class A		1,300			6,137			75			155			27			260			—	*		4			146			802
Less shares redeemed – Class A		(13,166	)		(21,923	)		(1,054	)		(476	)		(855	)		(990	)		(63	)		(53	)		(3,535	)		(6,938	)
Net Increase – Class A		10,688			18,516			1,368			1,829			1,791			1,829			115			258			346			8,351
Subscriptions – Class B		595			1,922			299			574			32			161			58			118			139			1,441
Shares issued in reinvestment and capital gains – Class B		528			2,814			31			73			9			137			—			2			31			211
Less shares redeemed – Class B		(3,813	)		(6,826	)		(332	)		(341	)		(291	)		(451	)		(35	)		(81	)		(708	)		(1,313	)
Net Increase (Decrease) – Class B		(2,690	)		(2,090	)		(2	)		306			(250	)		(153	)		23			39			(538	)		339
Subscriptions – Class C		3,731			6,667			906			524			466			321			43			92			486			2,455
Shares issued in reinvestment and capital gains – Class C		427			2,077			24			41			6			74			—			1			22			136
Less shares redeemed – Class C		(3,039	)		(5,835	)		(287	)		(201	)		(186	)		(363	)		(24	)		(33	)		(539	)		(1,172	)
Net Increase (Decrease) – Class C		1,119			2,909			643			364			286			32			19			60			(31	)		1,419
Subscriptions – Class Z		35,686			62,182			10,707			18,615			9,306			11,555			574			1,378			5,651			15,890
Shares issued in reinvestment and capital gains – Class Z		3,525			18,385			1,050			3,274			139			1,500			4			33			131			601
Less shares redeemed – Class Z		(21,759	)		(39,912	)		(4,553	)		(9,349	)		(2,974	)		(4,040	)		(204	)		(378	)		(2,851	)		(7,371	)
Net Increase – Class Z		17,452			40,655			7,204			12,540			6,471			9,015			374			1,033			2,931			9,120
Net Increase in Shares of Beneficial Interest		26,569			59,990			9,213			15,039			8,298			10,723			531			1,390			2,708			19,229

* Rounds to less than 500 shares.

See accompanying notes to financial statements.

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Columbia Acorn Family of Funds

>Financial Highlights

Columbia Acorn Fund	Class Z	(Unaudited) Six months ended June 30,			Year Ended December 31,
Selected data for a share outstanding throughout each period		2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period		$	28.17		$	26.45		$	22.56		$	15.50		$	17.88		$	17.21
Income from Investment Operations
Net investment income (a)			0.08			0.15			0.04			0.03			0.02			0.05
Net realized and unrealized gain (loss)			1.55			3.28			4.78			7.05			(2.40	)		1.01
Total from Investment Operations			1.63			3.43			4.82			7.08			(2.38	)		1.06
Less Distributions Declared to Shareholders
From net investment income			—			(0.15	)		(0.02	)		—			—			(0.04	)
From net realized gains			(0.31	)		(1.56	)		(0.91	)		(0.02	)		—			(0.35	)
Total Distributions Declared to Shareholders			(0.31	)		(1.71	)		(0.93	)		(0.02	)		—			(0.39	)
Net Asset Value, End of Period		$	29.49		$	28.17		$	26.45		$	22.56		$	15.50		$	17.88
Total Return (b)			5.81	%(c)(d)		13.11	%(c)		21.51	%(c)		45.68	%		(13.31	)%		6.14	%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)			0.73	%(f)		0.74	%		0.81	%		0.80	%		0.82	%		0.82	%
Net investment income (e)			0.53	%(f)		0.57	%		0.18	%		0.17	%		0.15	%		0.28	%
Waiver/reimbursement			0.01	%(f)		0.02	%		0.02	%		—			—			—
Portfolio turnover rate			11	%(d)		16	%		20	%		10	%		13	%		20	%
Net assets at end of period (in millions)		$	11,400		$	10,399		$	8,689		$	7,065		$	4,022		$	4,220

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Columbia Acorn International	Class Z	(Unaudited) Six months ended June 30,			Year Ended December 31,
Selected data for a share outstanding throughout each period		2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period		$	33.44		$	29.03		$	22.66		$	15.40		$	18.47		$	23.85
Income from Investment Operations
Net investment income (a)			0.29			0.34			0.25			0.21			0.14			0.12
Net realized and unrealized gain (loss)			4.48			5.87			6.37			7.13			(3.10	)		(5.11	)
Total from Investment Operations			4.77			6.21			6.62			7.34			(2.96	)		(4.99	)
Less Distributions Declared to Shareholders
From net investment income			(0.08	)		(0.72	)		(0.25	)		(0.08	)		(0.11	)		—
From net realized gains			(0.55	)		(1.08	)		—			—			—			(0.39	)
Total Distributions Declared to Shareholders			(0.63	)		(1.80	)		(0.25	)		(0.08	)		(0.11	)		(0.39	)
Net Asset Value, End of Period		$	37.58		$	33.44		$	29.03		$	22.66		$	15.40		$	18.47
Total Return (b)			14.27	%(c)(d)		21.81	%(c)		29.47	%(c)		47.80	%		(16.10	)%		(21.11	)%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)			0.94	%(f)		0.99	%		1.08	%		1.05	%		1.06	%		1.06	%
Net investment income (e)			1.54	%(f)		1.09	%		1.01	%		1.19	%		0.80	%		0.62	%
Waiver/reimbursement			0.01	%(f)		0.02	%		0.02	%		—			—			—
Portfolio turnover rate			19	%(d)		27	%		40	%		40	%		52	%		45	%
Net assets at end of period (in millions)		$	3,226		$	2,629		$	1,919		$	1,563		$	1,241		$	1,613

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Columbia Acorn USA	Class Z	(Unaudited) Six months ended June 30,			Year Ended December 31,
Selected data for a share outstanding throughout each period		2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period		$	27.03		$	25.20		$	21.01		$	14.28		$	17.52		$	14.90
Income from Investment Operations
Net investment income (loss) (a)			(0.01	)		0.07			(0.15	)		(0.13	)		(0.10	)		(0.08	)
Net realized and unrealized gain (loss)			0.60			3.18			4.48			6.86			(3.14	)		2.94
Total from Investment Operations			0.59			3.25			4.33			6.73			(3.24	)		2.86
Less Distributions Declared to Shareholders
From net investment income			—			(0.05	)		—			—			—			—
From net realized gains			(0.10	)		(1.37	)		(0.14	)		—			—			(0.24	)
Total Distributions Declared to Shareholders			(0.10	)		(1.42	)		(0.14	)		—			—			(0.24	)
Net Asset Value, End of Period		$	27.52		$	27.03		$	25.20		$	21.01		$	14.28		$	17.52
Total Return (b)			2.19	% (c)(d)		12.98	%(c)		20.62	%(c)		47.13	%		(18.49	)%		19.25	%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)			0.97	% (f)		1.01	%		1.09	%		1.11	%		1.17	%		1.17	%
Net investment income (loss) (e)			(0.05	)%(f)		0.28	%		(0.66	)%		(0.72	)%		(0.64	)%		(0.46	)%
Waiver/reimbursement			0.01	% (f)		0.01	%		0.02	%		—			—			—
Portfolio turnover rate			5	% (d)		13	%		18	%		7	%		31	%		24	%
Net assets at end of period (in millions)		$	1,132		$	937		$	646		$	502		$	235		$	229

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

See accompanying notes to financial statements.

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Columbia Acorn Family of Funds

>Financial Highlights, continued

Columbia Acorn International Select	Class Z	(Unaudited) Six months ended June 30,			Year Ended December 31,
Selected data for a share outstanding throughout each period		2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period		$	20.57		$	18.02		$	14.58		$	10.29		$	12.09		$	17.15
Income from Investment Operations
Net investment income (loss) (a)			0.11			0.13			0.04			0.06			0.03			(0.05	)
Net realized and unrealized gain (loss)			2.53			2.70			3.47			4.24			(1.83	)		(4.92	)
Total from Investment Operations			2.64			2.83			3.51			4.30			(1.80	)		(4.97	)
Less Distributions Declared to Shareholders
From net investment income			(0.05	)		(0.28	)		(0.07	)		(0.01	)		—			(0.01	)
From net realized gains			—			—			—			—			—			(0.08	)
Total Distributions Declared to Shareholders			(0.05	)		(0.28	)		(0.07	)		(0.01	)		—			(0.09	)
Net Asset Value, End of Period		$	23.16		$	20.57		$	18.02		$	14.58		$	10.29		$	12.09
Total Return (b)(c)			12.83	%(d)		15.98	%		24.14	%		41.79	%		(14.89	)%		(29.05	)%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)			1.29	%(f)		1.45	%		1.45	%		1.45	%		1.45	%		1.45	%
Net investment income (loss) (e)			0.95	%(f)		0.72	%		0.27	%		0.56	%		0.26	%		(0.32	)%
Waiver/reimbursement			0.01	%(f)		0.04	%		0.29	%		0.42	%		0.33	%		0.01	%
Portfolio turnover rate			30	%(d)		39	%		73	%		69	%		102	%		82	%
Net assets at end of period (in millions)		$	92		$	74		$	46		$	34		$	26		$	37

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Columbia Acorn Select	Class Z	(Unaudited) Six months ended June 30,			Year Ended December 31,
Selected data for a share outstanding throughout each period		2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period		$	22.77		$	21.13		$	18.20		$	14.04		$	15.23		$	14.13
Income from Investment Operations
Net investment loss (a)			(0.03	)		(0.03	)		(0.10	)		(0.10	)		(0.10	)		(0.05	)
Net realized and unrealized gain (loss)			1.27			2.35			3.47			4.39			(1.09	)		1.18
Total from Investment Operations			1.24			2.32			3.37			4.29			(1.19	)		1.13
Less Distributions Declared to Shareholders
From net investment income			(0.05	)		—			—			—			—			—
From net realized gains			(0.09	)		(0.68	)		(0.44	)		(0.13	)		—			(0.03	)
Total Distributions Declared to Shareholders			(0.14	)		(0.68	)		(0.44	)		(0.13	)		—			(0.03	)
Net Asset Value, End of Period		$	23.87		$	22.77		$	21.13		$	18.20		$	14.04		$	15.23
Total Return (b)			5.43	% (c)(d)		11.08	% (c)		18.58	%(c)		30.61	%		(7.81	)%(c)		8.00	%(c)
Ratios to Average Net Assets/Supplemental Data
Expenses			0.96	% (e)(f)		0.99	% (e)		1.13	% (e)		1.12	% (e)		1.26	% (e)		1.35	%
Net investment loss			(0.22	)%(e)(f)		(0.16	)%(e)		(0.52	)%(e)		(0.63	)%(e)		(0.67	)%(e)		(0.44	)%
Waiver/reimbursement			0.02	% (f)		0.03	%		0.02	%		—			0.01	%		0.03	%
Portfolio turnover rate			13	% (d)		19	%		34	%		16	%		40	%		82	%
Net assets at end of period (in millions)		$	791		$	688		$	445		$	294		$	93		$	70

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

See accompanying notes to financial statements.

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Columbia Acorn Family of Funds

>Notes to Financial Statements (Unaudited)

1. Nature of Operations

Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select and Columbia Acorn Select (the "Funds") are each a series of Columbia Acorn Trust (the "Trust"), an open-end management investment company organized as a Massachusetts business trust. The investment objective of each Fund is to seek long-term growth of capital. The Funds may issue an unlimited number of shares. The Funds currently offer four classes of shares: Class A, Class B, Class C and Class Z.

Class A shares are sold with a front-end sales charge. Class A shares bought without an initial sales charge in accounts aggregating up to $50 million at the time of purchase are subject to a 1.00% CDSC if the shares are sold within 12 months of the time of purchase.

Class B shares are subject to a CDSC if sold within six years of purchase. Class B shares will convert to Class A shares automatically eight years after purchase.

Class C shares are subject to a CDSC on redemptions made within one year after purchase.

Columbia Acorn International and Columbia Acorn International Select impose a 2% redemption fee on Class A, Class B and Class C shares that are owned 60 days or less. See "Fund Policy on Trading of Fund Shares" as disclosed within the Funds' prospectuses for more information.

Class Z shares are offered continuously at net asset value. There are certain restrictions on the purchase of Class Z shares. Generally, you may exchange your Class Z shares of a Fund for shares of another fund distributed by Columbia Management Distributors, Inc. at no additional charge. However, if you exchange Class Z shares of Columbia Acorn International or Columbia Acorn International Select that you have owned 60 days or less, the Fund will charge you a redemption fee of 2% of the redemption proceeds. In addition, if you redeem shares of Columbia Acorn International or Columbia Acorn International Select that you have owned 60 days or less, the Fund will charge you a redemption fee of 2% of redemption proceeds, with certain exceptions. See "Fund Policy on Trading of Fund Shares and Redemption Fees" as disclosed within the Funds' prospectuses for more information.

The financial highlights for Class A, Class B and Class C shares are presented in a separate semiannual report. The semiannual financial statements for the Columbia Thermostat Fund, another Fund of the Trust, begin on page 76 of this report.

Investment income, realized and unrealized gains and losses, and certain fund-level expenses are borne pro rata on the basis of the relative net assets of all classes, except each class bears certain expenses unique to that class such as distribution services, transfer agent and certain other class specific expenses. Differences in class expenses may result in payment of different dividend distributions for each class. All the share classes of the Trust have equal rights with respect to voting subject to class specific arrangements.

2. Significant Accounting Policies

>Security valuation

Securities of the Funds are valued at market value or, if a market quotation for a security is not readily available or is deemed not to be reliable because of events or circumstances that have occurred between the market quotation and the time as of which the security is to be valued, the security is valued at a fair value determined in accordance with procedures established by the Board of Trustees. Securities traded on securities exchanges or in over-the-counter markets in which transaction prices are reported are valued at the last sales price at the time of valuation. If a security is traded principally on the Nasdaq Stock Market Inc., the Nasdaq Official Closing Price will be applied. Securities for which there are no reported sales on the valuation date are valued at the latest bid quotation. Short-term debt obligations having a maturity of 60 days or less from the valuation date are valued on an amortized cost basis, which approximate fair value. Securities for which quotations are not available are valued at a fair value as determined in good faith by the Board of Trustees. The Trust has retained an independent statistical fair value pricing service to assist in the fair valuation process for securities principally traded in a foreign market in order to adjust for possible changes in value that may occur between the close of the foreign exchange and the time at which Fund shares are priced. If a security is valued at a "fair value," that value may be different from the last quoted market price for the security.

>Repurchase agreements

The Funds may engage in repurchase agreement transactions. The Funds, through their custodians, receive delivery of underlying securities collateralizing repurchase agreements. The Funds' investment adviser determines that the value of the underlying securities is at all times at least equal to the resale price. In the event of default or bankruptcy by the other party to the agreement, realization and/or retention of the collateral may be subject to legal proceedings.

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>Foreign currency translations

Values of investments denominated in foreign currencies are converted into U.S. dollars using the spot market rate of exchange at the time of valuation. Purchases and sales of investments and dividend and interest income are translated into U.S. dollars using the spot market rate of exchange prevailing on the respective dates of such transactions. The gain or loss resulting from changes in foreign exchange rates is included with net realized and unrealized gain or loss from investments, as appropriate.

>Security transactions and investment income

Security transactions are accounted for on the trade date (date the order to buy or sell is executed) and dividend income is recorded on the ex-dividend date, except that certain dividends from foreign securities are recorded as soon as the information is available to the Funds. Interest income is recorded on the accrual basis and includes amortization of discounts on short-term debt obligations and long-term debt obligations when required for federal income tax purposes. Realized gains and losses from security transactions are reported on an identified cost basis.

Awards from class action litigation may be recorded as a reduction of cost. If the Funds no longer own the applicable securities, the proceeds are recorded as realized gains.

The Funds estimate components of distributions from real estate investment trusts (REITs). Distributions received in excess of income are recorded as a reduction of the cost of the related investments. If the Funds no longer own the applicable securities, any distributions received in excess of income are recorded as realized gains.

>Restricted Securities

Restricted securities are securities that may only be resold upon registration under federal securities laws or in transactions exempt from registration. In some cases, the issuer of restricted securities has agreed to register such securities for resale at the issuer's expense either upon demand by the Funds or in connection with another registered offering of the securities. Many restricted securities may be resold in the secondary market in transactions exempt from registration. Such restricted securities may be determined to be liquid under criteria established by the Board of Trustees. The Funds will not incur any registration costs upon such resale.

>Use of estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and

assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results may differ from those estimates.

>Financial instruments

Each Fund may purchase or sell exchange-traded financial futures contracts, which are contracts that obligate that Fund to make or take delivery of a financial instrument or the cash value of a securities index at a specified future date at a specified price. The Funds enter into such contracts to hedge a portion of their portfolio. Gains and losses are reflected as "Net realized gain (loss) on Futures" in the Statements of Operations. Additionally, each Fund, except for Columbia Acorn USA and Columbia Acorn Select, may engage in portfolio hedging with respect to changes in foreign currency exchange rates by entering into forward foreign currency contracts to purchase or sell foreign currencies. The Statements of Operations reflect gains and losses as realized for closed forward foreign currency contracts and unrealized for open contracts. The Funds bear the market risk that arises from changes in the value of financial instruments and securities indices (futures contracts) or from changes in foreign currency rates (forward foreign currency contracts) and the credit risk should a counterparty fail to perform under such contracts.

None of the Funds entered into futures contracts or forward foreign currency contracts during the six months ended June 30, 2006.

>Fund share valuation

Fund shares are sold and redeemed on a continuing basis at net asset value. Net asset value per share is determined daily as of the close of trading on the New York Stock Exchange (the "Exchange") on each day the Exchange is open for trading. All income, expenses (other than the Class A, Class B and Class C 12b-1 service and distribution fees and Class A, Class B, Class C and Class Z shares transfer agent fees) and realized and unrealized gains (losses) of a Fund are allocated to each class proportionately on a daily basis for purposes of determining the net asset value of each class. Redemption fees are accounted for as an addition to paid in capital and are allocated to each class proportionately for purposes of determining the net asset value of each class.

>Custody fees/credits

Custody fees are reduced based on each Fund's cash balances maintained with the custodian. The Funds could have invested a portion of the assets utilized in connection with the expense offset arrangement in an income-producing asset if they had not entered into such an agreement. The amount is disclosed

Columbia Acorn Family of Funds

>Notes to Financial Statements (Unaudited), continued

as a reduction of total expenses in the Statements of Operations.

>Federal income taxes

The Funds have complied with the provisions of the Internal Revenue Code available to regulated investment companies and, in the manner provided therein, distribute all their taxable income, as well as any net realized gain on sales of investments and foreign currency transactions reportable for federal income tax purposes. Accordingly, the Funds paid no federal income taxes and no federal income tax provision was required.

>Foreign capital gains taxes

Realized gains in certain countries may be subject to foreign taxes at the fund level, at rates ranging from approximately 10% to 15%. The Funds accrue for such foreign taxes on net realized and unrealized gains at the appropriate rate for each jurisdiction.

>Distributions to Shareholders

Distributions to shareholders are recorded on the ex-date.

>Indemnification

In the normal course of business, each Fund enters into contracts that contain a variety of representations and warranties and which provide general indemnities. A Fund's maximum exposure under these arrangements is unknown, as this would involve future claims against the Fund. Also, under the Trust's organizational documents, the Trustees and Officers of the Trust are indemnified against certain liabilities that may arise out of their duties to the Trust. However, based on experience, the Funds expect the risk of loss due to these warranties and indemnities to be minimal.

3. Federal Tax Information

The tax character of distributions paid during the years ended December 31, 2005 was as follows:

	Ordinary Income*		Long-Term Capital Gains
(in thousands)
Columbia Acorn Fund	$	89,415	$	846,121
Columbia Acorn International		54,197		89,135
Columbia Acorn USA		1,825		56,868
Columbia Acorn International Select		1,037		—
Columbia Acorn Select		7,041		39,716

*For tax purposes short-term capital gains distributions, if any, are considered ordinary income distributions.

The following capital loss carryforwards, determined as of December 31, 2005, may be available to reduce taxable income

arising from future net realized gains on investments, if any, to the extent permitted by the Internal Revenue Code:

Year of Expiration	Columbia Acorn USA			Columbia Acorn International Select
(in thousands)
2009	$	2,023	*	$	10,593
2010		506			12,528
2011		—			2,488
TOTAL	$	2,529		$	25,609

*Of these carryforwards, $2,529 (expiring in 2009) remains from Columbia Acorn USA's merger with Stein Roe Small Company Growth Fund on 7/26/2002. Utilization of Stein Roe Small Company Growth Fund's losses could be subject to limitations imposed by the Internal Revenue Code.

The following capital loss carryforwards were utilized during the year ended December 31, 2005.

(In thousands)
Columbia Acorn International	$	62,579
Columbia Acorn USA		7,025
Columbia Acorn International Select		5,542

In June 2006, the Financial Accounting Standards Board ("FASB") issued FASB Interpretation No. 48, Accounting for Uncertainty in Income Taxes, an Interpretation of FASB Statement 109 (the "Interpretation"). This Interpretation is effective for fiscal years beginning after December 15, 2006 and is to be applied to all tax positions upon initial adoption. This Interpretation prescribes a minimum recognition threshold and measurement method for the financial statement recognition of tax positions taken or expected to be taken in a tax return and also requires certain expanded disclosures. Columbia Wanger Asset Management, L.P. ("Columbia WAM"), a wholly owned subsidiary of Columbia Management Group, Inc., which in turn is an indirect, wholly owned subsidiary of Bank of America Corporation ("BOA"), has recently begun to evaluate the application of this Interpretation to the Funds and has not at this time quantified the impact, if any, resulting from the adoption of this Interpretation on the Funds' financial statements.

4. Transactions with Affiliates

Columbia WAM furnishes continuing investment supervision to the Funds and is responsible for the overall management of the Funds' business affairs.

Effective August 1, 2006, under the Funds' investment management agreement, fees are accrued daily and paid monthly to Columbia WAM at the annual rates shown in the

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table below for Columbia Acorn USA and Columbia Acorn Select:

Columbia Acorn USA
Assets	Rate of Fee
Up to $200 million		0.940	%
$200 million to $500 million		0.890	%
$500 million to $2 billion		0.840	%
$2 billion to $3 billion		0.800	%
$3 billion and over		0.700	%
Columbia Acorn Select
Assets	Rate of Fee
Up to $700 million		0.850	%
$700 million to $2 billion		0.800	%
$2 billion to $3 billion		0.750	%
$3 billion and over		0.700	%

For the period covered by this report as provided under the Funds' investment management agreement, fees were accrued daily and paid monthly to Columbia WAM at the annual rates shown in the table below for each Fund.

Columbia Acorn Fund
Assets	Rate of Fee
Up to $700 million		0.740	%
$700 million to $2 billion		0.690	%
$2 billion to $6 billion		0.640	%
$6 billion and over		0.630	%
Columbia Acorn International
Assets	Rate of Fee
Up to $100 million		1.190	%
$100 million to $500 million		0.940	%
$500 million and over		0.740	%
Columbia Acorn USA
Assets	Rate of Fee
Up to $200 million		0.940	%
$200 million to $500 million		0.890	%
$500 million and over		0.840	%
Columbia Acorn Select
Assets	Rate of Fee
Up to $700 million		0.850	%
$700 million and over		0.800	%
Columbia Acorn International Select
All Assets		0.940	%

For the six months ended June 30, 2006, the Funds' effective investment advisory fee rates were as follows:

Columbia Acorn Fund	0.64	%
Columbia Acorn International	0.78	%
Columbia Acorn USA	0.87	%
Columbia Acorn International Select	0.94	%
Columbia Acorn Select	0.82	%

>Expense Limit

Columbia WAM has voluntarily agreed to reimburse the ordinary operating expenses (exclusive of interest, taxes and extraordinary expenses, if any) exceeding 1.45% of the average annual net assets for Columbia Acorn International Select Class Z shares and 1.35% of the average annual net assets for Columbia Acorn Select Class Z shares. This arrangement may be modified or terminated by either the Fund or Columbia WAM on 30 days notice.

Expenses reimbursed by Columbia WAM for Columbia Acorn International Select for the six months ended June 30, 2006 were $2,157.

Columbia WAM provides administrative services and receives an administration fee from the Funds at the following rates:

Columbia Acorn Trust
Average daily net asset value:
On the first $8 billion	0.05	%
Next $8 billion	0.04	%
Average daily net asset in excess of $16 billion	0.03	%

For the six months ended June 30, 2006, each Fund's effective administration fee rate was 0.041%. Columbia WAM has delegated to Columbia Management Advisors, LLC, an indirect, wholly owned subsidiary of BOA, responsibility to provide certain administrative services to the Funds.

Columbia Management Distributors, Inc. ("CMDI"), a wholly owned subsidiary of BOA, is the Funds' principal underwriter and receives no compensation on the sale of Class Z shares.

Each Fund has adopted a Rule 12b-1 plan which requires it to pay CMDI a service and distribution fee on the net assets attributable to Class A, Class B and Class C shares.

Columbia Management Services, Inc. (the "Transfer Agent"), a wholly owned subsidiary of BOA, provides shareholder services to the Funds and has contracted with Boston Financial Data Services ("BFDS") to serve as sub-transfer agent. For such services, the Transfer Agent receives a fee, paid monthly, at the annual rate of $21.00 per open account. The Transfer Agent also receives reimbursement for certain out-of-pocket expenses. The Transfer Agent waived the reimbursement for certain out-of-pocket expenses for the period covered by this report.

Expenses waived by the Transfer Agent for the six months ended June 30, 2006 were as follows:

(in thousands)
Columbia Acorn Fund	$	817
Columbia Acorn International		96
Columbia Acorn USA		48
Columbia Acorn International Select		7
Columbia Acorn Select		170

Columbia Acorn Family of Funds

>Notes to Financial Statements (Unaudited), continued

Certain officers and trustees of the Trust are also officers of Columbia WAM. The Trust makes no direct payments to its officers and trustees who are affiliated with Columbia WAM. Trustees' fees and expenses paid by the Funds for the six months ended June 30, 2006 were as follows:

(in thousands)
Columbia Acorn Fund	$	303
Columbia Acorn International		47
Columbia Acorn USA		21
Columbia Acorn International Select		1
Columbia Acorn Select		15

The Board of Trustees appointed a Chief Compliance Officer to the Trust in accordance with federal securities regulations. The Funds, along with other affiliated funds, will pay their pro-rata share of the expenses associated with the Office of the Chief Compliance Officer. These expenses are disclosed separately as "Compliance fees" in the Statements of Operations.

The Trust provides a deferred compensation plan for its trustees. Under that plan, a trustee may elect to defer all or a portion of his or her compensation. Amounts deferred are retained by the Trust and represent an unfunded obligation of the Trust. The value of amounts deferred is determined by reference to the change in value of Class Z shares of one or more series of the Trust or a money market fund as specified by the trustee. Benefits under the deferred compensation plan are payable upon retirement.

An affiliate may include any company in which a fund owns five percent or more of its outstanding voting securities. On June 30, 2006, Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA and Columbia Acorn Select each held five percent or more of the outstanding voting securities of one or more companies. Details of investments in those affiliated companies are presented on pages 33, 41, 49 and 58, respectively.

During the six months ended June 30, 2006, the Funds engaged in purchase and sale transactions with funds that have a common investment adviser (or affiliated investment advisers), common Directors/Trustees, and/or common Officers. Those transactions complied with Rule 17a-7 under the Investment Company Act of 1940 and were as follows:

	Purchases		Sales
(in thousands)
Columbia Acorn Fund	$	306	$	9,383
Columbia Acorn International		19,613		1,299
Columbia Acorn International Select		44		—
Columbia Acorn Select		—		97

5. Borrowing Arrangements

The Trust participates in a $150 million credit facility, which was entered into to facilitate portfolio liquidity. Interest is charged to each participating fund based on its borrowings at a rate per annum equal to the Federal Funds rate plus 0.50%. In addition, a commitment fee of 0.10% per annum is accrued and apportioned among the participating funds based on their pro-rata portion of the unutilized line of credit. The commitment fee is included in "Other expenses" in the Statements of Operations. No amounts were borrowed under this facility for the six months ended June 30, 2006.

6. Investment Transactions

The aggregate cost of purchases and proceeds from sales other than short-term obligations for the six months ended June 30, 2006 were:

Columbia Acorn Fund
(in thousands)
Investment securities
Purchases	$	2,536,172
Proceeds from sales		1,828,147
Columbia Acorn International
(in thousands)
Investment securities
Purchases	$	872,256
Proceeds from sales		618,788
Columbia Acorn USA
(in thousands)
Investment securities
Purchases	$	298,839
Proceeds from sales		66,493
Columbia Acorn International Select
(in thousands)
Investment securities
Purchases	$	40,440
Proceeds from sales		31,655
Columbia Acorn Select
(in thousands)
Investment securities
Purchases	$	273,545
Proceeds from sales		235,105

7. Redemption Fees

For the six months ended June 30, 2006, the redemption fees for Columbia Acorn International and Columbia Acorn International Select amounted to $107 and $4, respectively, and are accounted for as additions to paid in capital.

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8. Other

During the six months ended June 30, 2006, Columbia Acorn International sold foreign currency in error, resulting in a loss of $3,523. The Fund was reimbursed by Columbia WAM for the full amount of the loss.

9. Legal Proceedings

The Trust, Columbia WAM and the Trustees of the Trust are named as defendants in class and derivative complaints that have been consolidated in a Multi-District Action (the "MDL Action") in the federal district court of Maryland. These lawsuits contend that defendants permitted certain investors to market time their trades in certain Columbia Acorn Funds. The MDL Action is ongoing. However, all claims against Columbia Acorn Trust and the independent trustees of Columbia Acorn Trust have been dismissed.

The Trust and Columbia WAM are also defendants in a class action lawsuit that alleges, in summary, that the Trust and Columbia WAM exposed shareholders of Columbia Acorn International Fund to trading by market timers by allegedly: (a) failing to properly evaluate daily whether a significant event affecting the value of the Fund's securities had occurred after foreign markets had closed but before the calculation of the Fund's net asset value ("NAV"); (b) failing to implement the Fund's portfolio valuation and share pricing policies and procedures; and (c) failing to know and implement applicable rules and regulations concerning the calculation of NAV. The Seventh Circuit ruled that the plaintiffs' state law claims were preempted under federal law resulting in the dismissal of plaintiffs' complaint. Plaintiffs appealed the Seventh Circuit's ruling to the United States Supreme Court.

On March 21, 2005, a class action complaint was filed against the Columbia Acorn Trust and Columbia WAM seeking to rescind the Contingent Deferred Sales Charges assessed upon redemption of Class B shares of Columbia Acorn Funds due to the alleged market timing of the Columbia Acorn Funds. In addition to the rescission of sales charges, plaintiffs seek recovery of actual damages, attorneys' fees and costs. The case had been transferred to the MDL Action in the federal district court of Maryland.

On April 4, 2006, all of the parties to the MDL Action executed a letter settlement agreement intended to fully resolve all of the lawsuits consolidated in the MDL Action as well as the Fair Valuation Lawsuit. The settlement has not yet been finalized or approved by the court.

Columbia WAM, the Columbia Acorn Funds and the Trustees of the Trust are also defendants in a consolidated lawsuit filed in the federal district court of Massachusetts alleging that Columbia WAM used Fund assets to make undisclosed payments to brokers as an incentive for the brokers to market the Funds over other mutual funds to investors. The complaint alleges Columbia WAM and the Trustees of the Trust breached certain common law duties and federal laws.

On November 30, 2005, the court dismissed all of the claims alleged against all of the parties in the consolidated complaint. Plaintiffs timely filed a notice of appeal of the district court's dismissal order with the First Circuit Court of Appeals. The parties subsequently executed a settlement term sheet to fully resolve all claims in the litigation. The settlement has not yet been finalized or approved by the court.

The Trust and Columbia WAM intend to defend these suits vigorously.

As a result of these matters, or any adverse publicity or other developments resulting from them, there may be increased redemptions or reduced sales of Fund shares, which could increase transaction cost or operating expenses, or have other adverse consequences for the Funds. In connection with the events described in detail above, various parties have filed suit against certain funds, their Boards and/or BOA (and affiliated entities). These suits are ongoing. However, based on currently available information, the Columbia Acorn Trust believes that the likelihood that these lawsuits will have a material adverse impact on any Fund is remote, and Columbia WAM believes that the lawsuits are not likely to materially affect its ability to provide investment management services to the Funds.

For the six months ended June 30, 2006, Columbia Management has assumed consulting services and legal fees incurred by the Funds in connection with these matters and the amounts are as follows:

(in thousands)
Columbia Acorn Fund	$	84
Columbia Acorn International		16
Columbia Acorn USA		7
Columbia Acorn International Select		1
Columbia Acorn Select		9

Columbia Thermostat Fund

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares or Principal Amount (000)			Value (000)
		>Stock Funds: 50.9%
	1,828,532	Columbia Large Cap Enhanced Core Fund, Class Z	$	24,210
	1,542,750	Columbia Dividend Income Fund, Class Z		19,300
	394,773	Columbia Acorn International, Class Z		14,836
	498,693	Columbia Acorn Fund, Class Z		14,706
	1,035,323	Columbia Large Cap Value Fund, Class Z		14,536
	409,815	Columbia Acorn Select, Class Z		9,782
		Total Stock Funds (Cost: $90,716)		97,370
		>Bond Funds: 49.1%
	5,468,354	Columbia Intermediate Bond Fund, Class Z		47,083
	2,774,361	Columbia Federal Securities Fund, Class Z		28,187
	2,289,736	Columbia Conservative High Yield Fund, Class Z		18,730
		Total Bond Funds (Cost: $97,372)		94,000
Short-Term Obligation: 0.4%
$	685	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/03/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 12/12/08 market value $710 (repurchase proceeds: $685)		685
		(Cost: $685)		685
	Total Investments: 100.4% (Cost: $188,773)(a)			192,055
	Cash and Other Assets Less Liabilities: (0.4)%			(709	)
	Total Net Assets: 100%		$	191,346

>Notes to Statements of Investments (in thousands)

(a) At June 30, 2006, for federal income tax purposes cost of investments was $188,773 and net unrealized appreciation was $3,282 consisting of gross unrealized appreciation of $7,550 and gross unrealized depreciation of $4,268.

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Columbia Thermostat Fund

>Statement of Assets and Liabilities (Unaudited)

June 30, 2006

(in thousands)
Assets:
Unaffiliated investments, at value (cost: $685)	$	685
Affiliated investments, at value (cost: $188,088)		191,370
Cash		—	*
Receivable for: Fund shares sold		79
Dividends and interest		445
Expense reimbursement due from Investment Adviser		29
Total Assets		192,608
Liabilities:
Payable for:
Investments purchased		445
Fund shares redeemed		604
Management fee		16
Administration fee		7
Transfer agent fees		24
Trustees' fees		2
Custody fees		2
Reports to shareholders		57
12b-1 Service & Distribution fees		93
Deferred Trustees' fees		6
Other liabilities		6
Total Liabilities		1,262
Net Assets	$	191,346
Composition of Net Assets:
Paid in capital	$	180,294
Undistributed net investment income		3,327
Accumulated net realized gain		4,443
Net unrealized appreciation on investments		3,282
Net Assets	$	191,346
Net asset value per share – Class A (a)	$	12.53
(Net assets/shares)		($63,627/5,076)
Maximum offering price per share – Class A (b)	$	13.29
(Net asset value per share/front-end sales charge)		($12.53/0.9425)
Net asset value and offering price per share – Class B (a)	$	12.53
(Net assets/shares)		($73,634/5,876)
Net asset value and offering price per share – Class C (a)	$	12.52
(Net assets/shares)		($27,319/2,182)
Net asset value, offering and redemption price per share – Class Z	$	12.53
(Net assets/shares)		($26,766/2,136)

*Rounds to less than $500.

(a) Redemption price per share is equal to net asset value less any applicable contingent deferred sales charge.

(b) On sales of $50,000 or more the offering price is reduced.

See accompanying notes to financial statements.

Columbia Thermostat Fund

>Statement of Operations (Unaudited)
For the Six Months Ended June 30, 2006

(in thousands)
Investment Income:
Dividends from affiliated investment company shares	$	4,130
Interest income		17
Total Investment Income		4,147
Expenses:
Management fee		99
Administration fee		40
12b-1 Service and Distribution fees:
Class A		85
Class B		324
Class C		138
Transfer agent fees:
Class A		51
Class B		71
Class C		25
Class Z		13
Trustees' fees		2
Custody fees		2
Reports to shareholders		70
Compliance fees		3
Non-recurring costs (See Note 7)		1
Other expenses		55
Total expenses		979
Less custody fees paid indirectly		—	*
Less reimbursement of expenses by Investment Adviser		(153	)
Less fees waived by Transfer Agent		(31	)
Non-recurring costs reimbursed (See Note 7)		(1	)
Net Expenses		794
Net Investment Income		3,353
Net Realized and Unrealized Gain on Investments:
Net realized gain on:
Affiliated investments		4,104
Distributions from affiliated investment company shares		880
Net realized gain		4,984
Net change in unrealized appreciation (depreciation) on affiliated investments		(3,742	)
Net realized and unrealized gain		1,242
Net Increase in Net Assets from Operations	$	4,595

*Rounds to less than $500.

See accompanying notes to financial statements.

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Columbia Thermostat Fund

>Statement of Changes in Net Assets

Increase in Net Assets:	(Unaudited) Six months ended June 30,			Year ended December 31,
(in thousands)	2006			2005
Operations:
Net investment income	$	3,353		$	5,484
Net realized gain on affiliated investments and distributions from affiliated investment company shares		4,984			14,700
Net change in net unrealized appreciation (depreciation) on affiliated investments		(3,742	)		(10,409	)
Net Increase from Operations		4,595			9,775
Distributions Declared to Shareholders From:
Net investment income – Class A		(70	)		(2,069	)
Net realized gain – Class A		(1,229	)		(4,875	)
Net investment income – Class B		—	*		(1,831	)
Net realized gain – Class B		(1,409	)		(5,382	)
Net investment income – Class C		—			(617	)
Net realized gain – Class C		(520	)		(1,972	)
Net investment income – Class Z		(98	)		(797	)
Net realized gain – Class Z		(504	)		(1,697	)
Total Distributions to Shareholders		(3,830	)		(19,240	)
Share Transactions:
Subscriptions – Class A		4,262			15,104
Distributions reinvested – Class A		1,185			6,273
Redemptions – Class A		(13,279	)		(24,089	)
Net Decrease – Class A		(7,832	)		(2,712	)
Subscriptions – Class B		2,467			8,919
Distributions reinvested – Class B		1,280			6,512
Redemptions – Class B		(8,800	)		(11,391	)
Net Increase (Decrease) – Class B		(5,053	)		4,040
Subscriptions – Class C		2,960			5,664
Distributions reinvested – Class C		460			2,303
Redemptions – Class C		(4,467	)		(9,480	)
Net Decrease – Class C		(1,047	)		(1,513	)
Subscriptions – Class Z		2,323			5,843
Distributions reinvested – Class Z		578			2,384
Redemptions – Class Z		(1,744	)		(2,485	)
Net Increase – Class Z		1,157			5,742
Net Increase (Decrease) from Share Transactions		(12,775	)		5,557
Total Decrease in Net Assets		(12,010	)		(3,908	)
Net Assets:
Beginning of period		203,356			207,264
End of period	$	191,346		$	203,356
Undistributed Net Investment Income	$	3,327		$	142

*Rounds to less than $500.

See accompanying notes to financial statements.

Columbia Thermostat Fund

>Statement of Changes in Net Assets, continued

Changes in Shares of Beneficial Interest:	(Unaudited) Six months ended June 30,			Year ended December 31,
(in thousands)	2006			2005
Subscriptions – Class A		333			1,151
Shares issued in reinvestment and capital gains – Class A		95			497
Less shares redeemed – Class A		(1,039	)		(1,840	)
Net Decrease – Class A		(611	)		(192	)
Subscriptions – Class B		193			684
Shares issued in reinvestment and capital gains – Class B		102			515
Less shares redeemed – Class B		(689	)		(870	)
Net Increase (Decrease) – Class B		(394	)		329
Subscriptions – Class C		232			434
Shares issued in reinvestment and capital gains – Class C		37			182
Less shares redeemed – Class C		(350	)		(725	)
Net Decrease – Class C		(81	)		(109	)
Subscriptions – Class Z		182			446
Shares issued in reinvestment and capital gains – Class Z		46			189
Less shares redeemed – Class Z		(136	)		(189	)
Net Increase – Class Z		92			446
Net Increase (Decrease) in Shares of Beneficial Interest		(994	)		474

See accompanying notes to financial statements.

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Columbia Thermostat Fund

>Financial Highlights

Class Z	(Unaudited) Six months ended June 30,			Year Ended December 31,									Inception September 25, 2002 through December 31,
Selected data for a share outstanding throughout each period	2006			2005			2004			2003			2002
Net Asset Value, Beginning of Period	$	12.50			13.12		$	12.31		$	10.41		$	10.00
Income from Investment Operations
Net investment income (a)		0.25			0.43			0.31			0.19			0.04
Net realized and unrealized gain		0.07			0.28			0.82			1.87			0.37
Total from Investment Operations		0.32			0.71			1.13			2.06			0.41
Less Distributions Declared to Shareholders
From net investment income		(0.05	)		(0.42	)		(0.29	)		(0.16	)		—
From net realized gains		(0.24	)		(0.91	)		(0.03	)		(0.00	)(b)		—
Total Distributions Declared to Shareholders		(0.29	)		(1.33	)		(0.32	)		(0.16	)		—
Net Asset Value, End of Period	$	12.53		$	12.50		$	13.12		$	12.31		$	10.41
Total Return (c)(d)		2.56	%(e)		5.50	%		9.17	%		19.79	%		4.10	%(e)
Ratios to Average Net Assets/Supplemental Data
Expenses (f)		0.25	%(g)(h)		0.25	%(g)		0.25	%(g)		0.38	%(g)		0.62	%(h)(i)
Net investment income		3.99	%(g)(h)		3.28	%(g)		2.48	%(g)		1.64	%(g)		1.41	%(h)(i)
Reimbursement/waiver		0.12	%(h)		0.11	%		0.21	%		0.88	%		19.94	%(h)
Portfolio turnover rate		29	%(e)		96	%		67	%		61	%		11	%(e)
Net assets at end of period (in millions)	$	27		$	26		$	21		$	14		$	4

(a) Per share data was calculated using average shares outstanding during the period. Recognition of net investment income by the Fund is affected by the timing of the declaration of dividends by the underlying investment companies in which the Fund invests.

(b) Rounds to less than $0.01 per share.

(d) Had the Investment Adviser and/or Transfer Agent not reimbursed a portion of expenses, total return would have been reduced.

(e) Not annualized.

(f) Does not include expenses of the investment companies in which the Fund invests.

(g) The benefits derived from custody fees paid indirectly had no impact.

(h) Annualized.

(i) In accordance with a requirement of the Securities and Exchange Commission, the ratios reflect total expenses prior to the reduction of custody fees for cash balances the Fund maintains with the custodian ("custody fees paid indirectly"). The ratios of expenses to average daily net assets and net investment income to average daily net assets net of custody fees paid indirectly would have been 0.60% and 1.43%, respectively for the period ended December 31, 2002.

See accompanying notes to financial statements.

Columbia Thermostat Fund

>Notes to Financial Statements (Unaudited)

1. Nature of Operations

Columbia Thermostat Fund (the "Fund"), a series of Columbia Acorn Trust (the "Trust"), an open-end management investment company organized as a Massachusetts business trust. The Fund may issue an unlimited number of shares. The Fund currently offers four classes of shares: Class A, Class B, Class C and Class Z.

Class B shares are subject to a CDSC if sold within six years of purchase. Class B shares will convert to Class A shares automatically eight years after purchase.

Class C shares are subject to a CDSC on redemptions made within one year after purchase.

Class Z shares are offered continuously at net asset value. There are certain restrictions on the purchase of Class Z shares.

The financial highlights for Class A, Class B and Class C shares are presented in a separate semiannual report. The semiannual report for the other series of the Trust is also included in this report. Generally you may exchange your Class Z shares of the Fund for shares of another Fund distributed by Columbia Management Distributors, Inc. at no additional charge. See "Fund Policy on Trading of Fund Shares" as disclosed within the Fund's prospectus.

The investment objective of the Fund is to provide long-term total return. The Fund pursues its investment objective by investing in shares of other mutual funds. As a 'fund of funds' under normal circumstances, the Fund allocates at least 95% of its net assets among a selected group of stock and bond mutual funds (the "Portfolio Funds") according to the current level of the Standard & Poor's 500 Stock Index in relation to predetermined ranges set by the Fund's investment adviser. As of June 30, 2006, the Fund invested in six stock Portfolio Funds (Columbia Acorn Fund, Columbia Acorn Select, Columbia Large Cap Value Fund, Columbia Acorn International, Columbia Dividend Income Fund and Columbia Large Cap Enhanced Core Fund) and three bond Portfolio Funds (Columbia Federal Securities Fund, Columbia Intermediate Bond Fund and Columbia Conservative High Yield Fund). The Fund also may invest up to 5% of its net assets plus any cash received that day in cash, repurchase agreements, high quality short-term paper and government securities.

Investment income, realized and unrealized gains and losses, and certain fund-level expenses are borne pro rata on the basis of the relative net assets of all classes, except each class bears certain expenses unique to that class such as distribution services, transfer agent, and certain other class specific expenses. Differences in class expenses may result in payment of different dividend distributions for each class. All the share classes of the Trust have equal rights with respect to voting subject to class specific arrangements.

2. Significant Accounting Policies

>Security valuation

Investments in Portfolio Funds are valued at their net asset value as reported by the underlying funds. High quality short-term paper and government securities having a maturity of 60 days or less from the valuation date are valued on an amortized cost basis, which approximates fair value.

>Repurchase agreements

The Fund may engage in repurchase agreement transactions. The Fund, through its custodian, receives delivery of underlying securities collateralizing each repurchase agreement. The Fund's investment adviser determines that the value of the underlying securities is at all times at least equal to the resale price. In the event of default or bankruptcy by the other party to the agreement, realization and/or retention of the collateral may be subject to legal proceedings.

>Security transactions and investment income

Portfolio Fund transactions are accounted for on the trade date (date the order to buy or sell is executed). Dividend income and realized gain distributions from other funds are recorded on the ex-dividend date. Interest income is recorded on the accrual basis and includes amortization of discounts on short-term debt obligations when required for federal income tax purposes. Realized gains and losses from security transactions are reported on an identified cost basis. Awards from class action litigation may be recorded as a reduction of cost by Portfolio Funds. If the Portfolio Fund no longer owns the applicable securities, the proceeds are recorded as realized gains.

>Use of estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results may differ from those estimates.

>Fund share valuation

Fund shares are sold and redeemed on a continuing basis at net asset value. Net asset value per share is determined daily

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as of the close of trading on the New York Stock Exchange (the "Exchange") on each day the Exchange is open for trading. All income, expenses (other than Class A, Class B and Class C 12b-1 service and distribution fees, and Class A, Class B, Class C and Class Z transfer agent fees) and realized and unrealized gains (losses) of the Fund are allocated to each class proportionately on a daily basis for purposes of determining the net asset value of each class.

>Custody fees/credits

Custody fees are reduced based on the Fund's cash balance maintained with the custodian. The Fund could have invested a portion of assets utilized in connection with the expense offset arrangement in an income-producing asset if it had not entered into such an agreement. The amount is disclosed as a reduction of total expenses in the Statement of Operations.

>Federal income taxes

The Fund has complied with the provisions of the Internal Revenue Code available to regulated investment companies and, in the manner provided therein, distributes all of its taxable income, as well as any net realized gain on sales of Portfolio Fund shares and any distributions of net realized gains received by the Fund from its Portfolio Funds, reportable for federal income tax purposes. Accordingly, the Fund paid no federal income taxes and no federal income tax provision was required.

>Distributions to Shareholders

Distributions to shareholders are recorded on the ex-date.

>Indemnification

In the normal course of business, the Fund enters into contracts that contain a variety of representations and warranties and which provide general indemnities. The Funds' maximum exposure under these arrangements is unknown, as this would involve future claims against the Fund. Also, under the Trust's organizational documents, the Trustees and Officers of the Trust are indemnified against certain liabilities that may arise out of their duties to the Trust. However, based on experience, the Fund expects the risk of loss due to these warranties and indemnities to be minimal.

3. Federal Tax Information

The tax character of distributions paid during the year ended December 31, 2005 was as follows:

(in thousands)
Distributions paid from:
Ordinary Income*	$	8,262
Long-Term Capital Gains		10,978

*For tax purposes short-term capital gains distributions, if any, are considered ordinary income distributions.

In June 2006, the Financial Accounting Standards Board ("FASB") issued FASB Interpretation No. 48, Accounting for Uncertainty in Income Taxes, an Interpretation of FASB Statement 109 (the "Interpretation"). This Interpretation is effective for fiscal years beginning after December 15, 2006 and is to be applied to all tax positions upon initial adoption. This Interpretation prescribes a minimum recognition threshold and measurement method for the financial statement recognition of tax positions taken or expected to be taken in a tax return and also requires certain expanded disclosures. Columbia Wanger Asset Management, L.P. ("Columbia WAM"), a wholly owned subsidiary of Columbia Management Group, Inc., which in turn is an indirect, wholly owned subsidiary of Bank of America Corporation ("BOA"), has recently begun to evaluate the application of this Interpretation to the Fund and has not at this time quantified the impact, if any, resulting from the adoption of this Interpretation on the Fund's financial statements.

4. Transactions with Affiliates

Columbia WAM furnishes continuing investment supervision to the Fund and is responsible for the overall management of the Fund's business affairs.

Under the Fund's investment management agreement, fees are accrued daily and paid monthly to Columbia WAM at the annual rate of 0.10% of the Fund's average daily net assets.

>Expense Limit

Columbia WAM has contractually agreed to reimburse the direct operating expenses (exclusive of interest and fees on borrowings and expenses associated with the Fund's investment in other investment companies) exceeding 0.25% of the average annual net assets of the Fund's Class Z shares annually through April 30, 2007.

Fees reimbursed amounted to $153,234 for the six months ended June 30, 2006.

Columbia WAM has the right to recoup expense reimbursement payments made to the Fund through December 31, 2006. No expenses were recouped through June 30, 2006.

Columbia WAM provides administrative services and receives an administration fee from the Fund at the following annual rates:

Columbia Acorn Trust
Average daily net asset value:
On the first $8 billion	0.05	%
Next $8 billion	0.04	%
Average daily net asset value in excess of $16 billion	0.03	%

For the six months ended June 30, 2006, the Fund's effective administration fee rate was 0.041%. Columbia WAM has delegated to Columbia Management Advisors, LLC, an indirect, wholly owned subsidiary of BOA, responsibility to provide certain administrative services to the Fund.

Columbia Thermostat Fund

>Notes to Financial Statements (Unaudited), continued

Columbia Management Distributors, Inc. ("CMDI"), a wholly owned subsidiary of BOA, is the Fund's principal indirect underwriter and receives no compensation on the sale of Class Z shares.

The Fund has adopted a 12b-1 plan which requires it to pay CMDI a service and distribution fee on net assets attributable to Class A, Class B and Class C shares.

Columbia Management Services, Inc. (the "Transfer Agent"), a wholly owned subsidiary of BOA, provides shareholder services to the Fund and has contracted with Boston Financial Data Services ("BFDS") to serve as sub-transfer agent. For such services, the Transfer Agent receives a fee, paid monthly, at the annual rate of $21.00 per open account. The Transfer Agent also receives reimbursement for certain out-of-pocket expenses. The Transfer Agent waived the reimbursement for certain out-of-pocket expenses for the period covered by this report. Expenses waived by the Transfer Agent for the six months ended June 30, 2006 were $30,576.

Certain officers and trustees of the Trust are also officers of Columbia WAM. The Trust makes no direct payments to its officers and trustees who are affiliated with Columbia WAM. Trustees' fees and expenses paid by the Fund for the six months ended June 30, 2006 were $2,362.

The Board of Trustees appointed a Chief Compliance Officer to the Trust in accordance with federal securities regulations. The Fund, along with other affiliated funds, will pay its pro-rata share of the expenses associated with the Office of the Chief Compliance Officer. This expense is disclosed separately as "Compliance fees" in the Statement of Operations.

5. Borrowing Arrangements

The Trust participates in a $150 million credit facility, which was entered into to facilitate portfolio liquidity. Interest is charged to each participating fund based on its borrowings at a rate per annum equal to the Federal Funds rate plus 0.50%. In addition, a commitment fee of 0.10% per annum is accrued and apportioned among the participating funds based on their pro-rata portion of the unutilized line of credit. The commitment fee is included in "Other expenses" in the Statement of Operations. No amounts were borrowed under this facility for the six months ended June 30, 2006.

6. Investment Transactions

The aggregate cost of purchases and proceeds from sales other than short-term obligations for the six months ended June 30, 2006 were:

(in thousands)
Purchases	$	57,973
Proceeds from sales		69,846

7. Legal Proceedings

The Trust, Columbia WAM and the Trustees of the Trust are named as defendants in class and derivative complaints which have been consolidated in a Multi-District Action (the "MDL Action") in the federal district court of Maryland. These lawsuits contend that defendants permitted certain investors to market time their trades in certain Columbia Acorn Funds. The MDL Action is ongoing. However, all claims against Columbia Acorn Trust and the independent trustees of Columbia Acorn Trust have been dismissed.

1-800-922-6769

The Trust and Columbia WAM intend to defend these suits vigorously.

As a result of these matters or any adverse publicity or other developments resulting from them, there may be increased redemptions or reduced sales of Fund shares, which could increase transaction cost or operating expenses, or have other adverse consequences for the Fund. In connection with the events described in detail above, various parties have filed suit against certain funds, their Boards and/or BOA (and affiliated entities). These suits are ongoing. However, based on currently available information, the Columbia Acorn Trust believes that the likelihood that these lawsuits will have a material adverse impact on any Fund is remote, and Columbia WAM believes that the lawsuits are not likely to materially affect its ability to provide investment management services to the Funds.

For the six months ended June 30, 2006, Columbia Management has assumed $934 of consulting services and legal fees incurred by the Fund in connection with these matters.

[Excerpts from:]

Columbia Acorn Trust

Management Fee Evaluation of the Senior Officer

Prepared Pursuant to the New York Attorney General's
Assurance of Discontinuance

Robert P. Scales
Senior Vice President,
Chief Legal Officer
and General Counsel

2006

Introduction

The New York Attorney General's Assurance of Discontinuance ("Order") entered into by Columbia Management Advisors, Inc. ("CMAI") and Columbia Management Distributors, Inc., ("CMDI" and collectively with "CMAI," "CMG") in February 2005, allows CMAI to manage or advise a mutual fund, including the Acorn Trust's family of funds (the "Acorn Funds" or "Acorn" or "Trust"), only if the trustees of the Acorn Funds appoint a "Senior Officer" to perform specified duties and responsibilities. One of these responsibilities includes "managing the process by which proposed management fees (including but not limited to, advisory fees) to be charged the [Acorn Funds] are negotiated so that they are negotiated in a manner which is at arms' length and reasonable and consistent with this Assurance of Discontinuance."

The Order also provides that the Board of Trustees of the Acorn Funds ("Board") must determine the reasonableness of proposed "management fees" by using either an annual competitive bidding process supervised by the Senior Officer or Independent Fee Consultant, or by obtaining "an annual independent written evaluation prepared by or under the direction of the Senior Officer or the Independent Fee Consultant."

"Management fees" are only part of the costs and expenses paid by mutual fund shareholders. The expenses can vary depending upon the class of shares held but usually include: (1) investment management or advisory fees to compensate analysts and portfolio managers for stock research and portfolio management, as well as the cost of operating a trading desk; (2) administrative expenses incurred to prepare registration statements and tax returns, calculate the Funds' net asset values, maintain effective compliance procedures and perform recordkeeping services; (3) transfer agency costs for establishing accounts, accepting and disbursing funds, as well as overseeing trading in Fund shares; (4) custodial expenses incurred to hold the securities purchased by the Funds; and (5) distribution expenses, including commissions paid to brokers that sell the Fund shares to investors.

Columbia Wanger Asset Management, L.P. ("CWAM"), the adviser to the Acorn Funds, has proposed that the Trust enter into separate agreements governing the first two categories listed above: an advisory agreement governing portfolio management, and an administration agreement governing certain administration and clerical services. Together the fees paid under these two agreements are referred to as "management fees." Other fund expenses are governed by separate agreements, in particular agreements with two CWAM affiliates: CMDI, the broker-dealer that underwrites and distributes the Acorn Funds' shares, and Columbia Management Services, Inc. ("CMSI"), the Funds' transfer agent. In conformity with the terms of the Order, this evaluation, therefore, addresses only the advisory and administrative contracts between CWAM and the Trust, and does not extend to the other agreements.

According to the Order, the Senior Officer's evaluation must consider at least the following:

(1) Management fees (including components thereof) charged to institutional and other clients of CWAM for like services;

(2) Management fees (including any components thereof) charged by other mutual fund companies for like services;

(3) Costs to CWAM and its affiliates of supplying services pursuant to the management fee agreements, excluding any intra-corporate profit;

(4) Profit margins of CWAM and its affiliates from supplying such services;

(5) Possible economies of scale as the Acorn Funds grow larger; and

(6) The nature and quality of CWAM's services, including the performance of each Acorn Fund.

On November 16, 2004, the Board appointed me Senior Officer under the Order. The Board also determined not to pursue a competitive bidding process and instead, charged me with the responsibility of evaluating the Acorn Funds' proposed advisory and administrative fee contracts with CWAM in conformity with the requirements of the Order. This Report is an annual evaluation required under the Order. In discharging their responsibilities, the independent Trustees have also consulted independent, outside counsel.

2005 Evaluation

This is the second annual evaluation prepared in connection with the Order. The first annual evaluation ("2005 Evaluation") was issued on July 20, 2005. This evaluation follows the same structure as the 2005 Evaluation. Some areas are given more emphasis here, while others are given less. Still, the fundamental information gathered for this evaluation is the largely the same as last year. I have noted in this Report where methodologies diverged significantly.

This evaluation was performed in cooperation and regular communication with the Contract Review Committee of the Board of Trustees.

Process and Independence

The objectives of the Order are to insure the independent evaluation of the advisory fees paid by the Acorn Funds as well as to insure that all relevant factors are considered. In my view, the contract renewal process has been conducted at arms-length and with independence in gathering, considering and evaluating all relevant data. At the outset of the process, the Trustees sought and obtained from CWAM and CMG a comprehensive compilation of data regarding Fund performance and expense, adviser profitability, and other information. In advance of the contract renewal process, the Board also explored CWAM's potential capacity restraints, an issue posed by the size of the Acorn Fund and by some of the observations from the 2005 Evaluation. Performance and expense data was obtained from both Morningstar and Lipper, the leading consultants in this area. The rankings prepared by Morningstar and Lipper were independent and were not influenced by the adviser. CWAM itself identified what it considers its competition in formulating its own peer group, and the Trustees considered that data as well.

In the course of its work, the Contract Committee gave careful consideration to the conclusions and recommendations contained in the 2005 Evaluation. In particular, the Contract Committee considered the possible introduction of a two-tiered fee structure that would set fees on the basis of a combined CWAM complex level and individual fund level. The Committee concluded that such a fee structure might be confusing to shareholders, though it has not foreclosed such a structure in the future. The Committee is continuing to consider whether economies of scale are appropriately reflected in the Funds' fee schedules.

My evaluation of the advisory contract was shaped, as it was last year, by my experience as Acorn's Chief Compliance Officer ("CCO"). As CCO, I report solely to the Board and have no reporting obligation to or employment relationship with CMG or its affiliates, except for administrative purposes. This too contributes to the independence of this evaluation. I have commented on compliance matters in evaluating the quality of service provided by CWAM.

This Report, its supporting materials and the data contained in other materials submitted to the Contract Committee of the Board, in my view, provide a thorough factual basis upon which the Board, in consultation with independent counsel as it deems appropriate, may conduct management fee negotiations that are in the best interests of the Acorn Funds' shareholders.

The Fee Reductions Mandated under the Order

Under the terms of the Order, CMG agreed to secure certain management fee reductions for the mutual funds advised by its affiliate investment advisers. In some instances, breakpoints were also established. Although neither CWAM nor the Trust was a party to the Order, CWAM offered and the Board accepted certain advisory fee reductions last year. By the terms of the Order, these fees may not be increased before November 30, 2009. I have used these advisory fee levels in my evaluation because they are the fees in the current agreements that CWAM proposes should be continued. Hence, these fee levels are the starting point of an evaluation.

Conclusions

My review of the data and other material above leads to the following conclusions with respect to the factors identified in the Order.

1. Performance. The domestic Funds generally have achieved outstanding performance. The Acorn Fund, Acorn USA and Acorn Select all rank very favorably against their peers. The international Funds have not, however, performed nearly as well as the domestic funds, and continue to lag their benchmarks and peers. Management is taking steps to improve the performance of these funds.

2. Management Fees relative to Peers. The management fee rankings for most of the Funds are generally more favorable to shareholders than those of their peer group funds. Management fees do vary by Fund. Acorn Fund is the least expensive and the Acorn USA the most expensive. Acorn USA and Acorn Select were ranked by both Lipper and Morningstar below many of their peers, and therefore impose higher fees than do some of their competitors.

3. Administrative Fees. The Acorn Funds' administrative fee, which is uniform across all Funds, is at a level comparable to that of most peers, provides for appropriate services to Funds, and affords breakpoints that lower the fee as assets increase.

4. Management Fees relative to Institutional and Other Mutual Fund Accounts. CWAM's focus is on its mutual funds. It does not actively seek to manage separate or institutional accounts. The few institutional accounts it does manage vary in rate structures. Some pay advisory fees commensurate with or higher than the Acorn Funds. In a few instances, however, institutional accounts pay lower advisory fees than do the Acorn Funds. One particular institutional account is significant in size and has been under CWAM's management for over 25 years. Finally, in two instances, the Acorn Funds pay slightly higher fees than do similar funds sold through insurance companies.

5. Costs to CWAM and its Affiliates. CWAM's direct costs do not appear excessive, and in some areas have declined in the past year. Indirect costs allocated to CWAM by its parent organization, however, have increased substantially. CWAM's affiliates report operating losses and therefore do not appear to profit from CWAM's advisory agreement with the Acorn Funds.

6. Profit Margins. CWAM's firm-wide, pre-marketing expense profit margins are at the top of the industry, though these comparisons are hampered by limited industry data. High profit margins are not unexpected for firms that manage large, successful funds and have provided outstanding investment performance for investors.

7. Economies of Scale. Economies of scale do exist at CWAM and will expand as the assets of the Acorn Funds get larger. They are, however, only partially reflected in the management fee schedule for the Funds. If the Acorn Funds' assets continue to grow, under the Funds' current fee schedules, shareholders might not benefit in a manner generally commensurate with CWAM's increased profits.

8. Nature and Quality of Services. This category includes a variety of considerations that are difficult to quantify, yet can have a significant bearing on the performance of the Acorn Funds. Several areas merit comment.

a. Capacity. The Funds have continued to grow, posing ever greater challenges in deploying assets effectively. While trends here merit continued monitoring, CWAM appears to be managing assets effectively.

b. Compliance. CWAM has a reasonably designed compliance program that protects shareholders.

c. Administrative Services. The Acorn Funds benefit from a variety of administrative services that are performed by CWAM and CMAI.

In my opinion, the process of negotiating an advisory contract for the Acorn Funds has been conducted thoroughly and at arms' length. Further, the Trustees have sufficient information to evaluate management's proposal, and negotiate contract terms that are in the best interests of fund shareholders.

Recommendations

I believe the Trustees should:

1. Continue to consider ways to restructure the advisory fee beyond the current breakpoint schedule to reflect more fully economies of scale.

2. Monitor the performance of Acorn International and Acorn International Select.

3. Continue to monitor CWAM's capacity limitations to insure that Acorn Fund's expanding assets do not impair investment performance.

Robert P. Scales

July 18, 2006

Columbia Acorn Family of Funds Class Z Share Information

Minimum Initial Investment in Columbia Acorn International, Columbia Acorn International Select and Columbia Thermostat Fund	$	1,000
	$	1,000	for an IRA
Minimum Initial Investment in Columbia Acorn Fund and Columbia Acorn USA	$75,000
Minimum Initial Investment in Columbia Acorn Select	$50,000
Minimum Subsequent Investment in all Funds	$50
Exchange Fee	None

Columbia Acorn Fund	ACRNX
Management Fee	0.64	%
12b-1 Fee	None
Other Expenses	0.09	%
Net Expense Ratio	0.73	%
Columbia Acorn International	ACINX
Management Fee	0.78	%
12b-1 Fee	None
Other Expenses	0.16	%
Net Expense Ratio	0.94	%
Columbia Acorn USA	AUSAX
Management Fee	0.87	%
12b-1 Fee	None
Other Expenses	0.10	%
Net Expense Ratio	0.97	%
Columbia Acorn International Select	ACFFX
Management Fee	0.94	%
12b-1 Fee	None
Other Expenses	0.35	%
Net Expense Ratio	1.29	%
Columbia Acorn Select	ACTWX
Management Fee	0.82	%
12b-1 Fee	None
Other Expenses	0.14	%
Net Expense Ratio	0.96	%
Columbia Thermostat Fund	COTZX
Management Fee	0.10	%
12b-1 Fee	None
Other Expenses	0.15	%
Net Expense Ratio	0.25	%*

Fees and expenses are for the six months ended June 30, 2006 and for Columbia Thermostat Fund include the effect of Columbia Wanger Asset Management's undertaking to reimburse this Fund for any ordinary operating expenses, net of custody fees paid indirectly, 0.25% of the average net assets. Columbia Thermostat Fund's reimbursement arrangement is contractual through April 30, 2007. The Funds' adviser and/or affiliates have voluntarily agreed to waive a portion of "other expenses" for the Columbia Acorn Family of Funds.

* Does not include estimated fees and expenses of 0.71% incurred by the Fund from the underlying portfolio funds.

Columbia Acorn

Family of Funds

Trustees

Robert E. Nason

Chairman

Allan B. Muchin

Vice Chairman

Margaret Eisen

Jerome Kahn, Jr.

Steven N. Kaplan

David C. Kleinman

Charles P. McQuaid

James A. Star

Ralph Wanger

Patricia H. Werhane

John A. Wing

Officers

Charles P. McQuaid

President

Ben Andrews

Vice President

Michael G. Clarke

Assistant Treasurer

Jeffrey R. Coleman

Assistant Treasurer

J. Kevin Connaughton

Assistant Treasurer

P. Zachary Egan

Vice President

John M. Kunka

Assistant Treasurer

Joseph C. LaPalm

Vice President

Bruce H. Lauer

Vice President, Treasurer and Secretary

Louis J. Mendes III

Vice President

Robert A. Mohn

Vice President

Christopher J. Olson

Vice President

Michelle H. Rhee

Assistant Secretary

Linda K. Roth-Wiszowaty

Assistant Secretary

Robert P. Scales

Senior Vice President, Chief Legal Officer
and General Counsel

Investment Adviser

Columbia Wanger Asset Management, L.P.
227 West Monroe Street, Suite 3000
Chicago, Illinois 60606

1-800-922-6769

Distributor

Columbia Management Distributors, Inc.
One Financial Center
Boston, Massachusetts 02111-2621

Transfer Agent, Dividend Disbursing Agent

Columbia Management Services, Inc.
P.O. Box 8081
Boston, Massachusetts 02266-8081

1-800-345-6611

Legal Counsel

Bell, Boyd & Lloyd LLC
Chicago, Illinois

This report, including the schedules of investments, is submitted for the general information of the shareholders of Columbia Acorn Trust. This report is not authorized for distribution unless preceded or accompanied by a prospectus. An investor should carefully consider charges and expenses before investing. To obtain a prospectus containing this and other information, please call (800) 922-6769 or visit our website (shown below). Please read the prospectus carefully before you invest or send money.

A description of the policies and procedures that the Funds use to determine how to vote proxies and a copy of the Funds' voting record are available (i) without charge, upon request, by calling 800-922-6769 and (ii) on the Securities and Exchange Commission's website at www.sec.gov. Information regarding how the Funds voted proxies relating to portfolio securities during the 12-month period ended June 30, is available from the SEC's website. Information regarding how the Funds voted proxies relating to portfolio securities is also available from the Fund's website.

The Funds file a complete schedule of portfolio holdings with the SEC for the first and third quarters of each fiscal year on Form N-Q. The Funds' Form N-Q is available on the SEC's website at www.sec.gov and may be reviewed and copied at the SEC's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling 1-800-SEC-0330.

Find out what's new – visit our web site at:

www.columbiafunds.com

Our e-mail address is:

ServiceInquiries@ColumbiaManagement.com

Shareholders should not include personal information such as account numbers, Social Security numbers or taxpayer identification numbers in e-mail. We are unable to accept account transactions sent via e-mail.

1-800-922-6769

Directions to the 2006 Annual Shareholder Information Meeting

The Chase Bank Auditorium is located on the Plaza Level of the Chase Bank building. The Chase Bank building is located in the center of the Loop, bordered by Dearborn Street on the east, Madison Street on the north, Clark Street on the west and Monroe Street on the south.

From the south:

Take 1-57 (which merges with I-94, also known as the Dan Ryan Expressway). Take the Dan Ryan into Chicago. Follow the signs for the Kennedy Expressway West. Travel on the Kennedy and exit using the Monroe Street exit. Turn right (east) from the exit onto Monroe Street. Proceed east on Monroe Street to Dearborn.

From the north:

Take the Kennedy Expressway (I-90/94) south to Chicago. Exit in the city at Monroe Street. Turn left (east) from the exit onto Monroe Street. Proceed east on Monroe Street to Dearborn.

From the west:

Take the Eisenhower Expressway (I-290) from the west. This becomes Congress Street in the city. Take Congress east to Dearborn Street. Turn left (north) on Dearborn to Monroe Street.

From the southwest:

Take the Stevenson Expressway (I-55). Exit to the Kennedy Expressway (North-Wisconsin). Travel on the Kennedy and exit using the Monroe Street exit. Turn right (east) from the exit onto Monroe Street. Proceed east on Monroe Street to Dearborn.

Parking Information for 2006 Annual Shareholder Information Meeting

A public lot is located at 172 West Madison, between Wells and LaSalle, on the north side of the street. The entrance is on Madison. Madison is a one-way west street. This lot is approximately two blocks west of the Chase Bank building.

Valet parking is available at 183 West Monroe, between Wells and LaSalle, on the south side of the street. The entrance is on Monroe. Monroe is a one-way east street. No vans or trucks are allowed to park at this lot. This lot is approximately three blocks west of the Chase Bank building.

55 East Monroe (formerly Mid-Continental Plaza Parking) is located on East Monroe Street two and one half blocks east of the Chase Bank building. The entrance is on the south side (right) of Monroe Street, between Wabash and Michigan Avenues. Monroe is a one-way street east.

Grant Park Underground (indoor) parking is located three blocks east of the Chase Bank building on Monroe Street. The entrance is on the north side of Monroe Street between Columbus Drive and Lake Shore. Monroe is two-way between Lake Shore Drive and Michigan Avenue. West of Michigan, Monroe is a one-way east.

For directions using public transportation, call (312) 836-7000 for CTA travel information or visit the CTA website at www.transitchicago.com. For Metra information call (312) 322-6777 during business hours or find information at www.metrarail.com.

Save the Date!

September 26, 2006

Meet your portfolio managers, analysts
and fellow shareholders

Columbia Acorn Funds
2006 Annual Shareholder
Information Meeting

Chase Auditorium
(formerly Bank One Auditorium)
38 South Dearborn Street
Chicago, IL 60602

Columbia Acorn Family of Funds

Class Z Shares

Semiannual Report – June 30, 2006

Columbia Management_®

PRESORTED

FIRST-CLASS MAIL

U.S. POSTAGE PAID

HOLLISTON, MA

PERMIT NO. 20

One Financial Center, Boston, MA 02111-2621

800-345-6611 www.columbiafunds.com

SHC-44/111880-0606 (08/06) 06/27765

Columbia Management®

Look inside for details on the 2006 Columbia Acorn Funds Annual Shareholder Information Meeting.

Columbia Acorn Funds

Class ABC Shares

Semiannual Report

June 30, 2006

n Columbia Acorn Fund

n Columbia Acorn International

n Columbia Acorn USA

n Columbia Acorn International Select

n Columbia Acorn Select

n Columbia Thermostat Fund

^{Managed by Columbia Wanger Asset Management, L.P.}

NOT FDIC-INSURED

May Lose Value

No Bank Guarantee

Please join us at the

2006

Annual Shareholder Information Meeting

September 26, 2006
9 a.m. – 10 a.m. Central time

Chase Auditorium
(formerly Bank One),
Plaza Level
38 South Dearborn Street
Chicago, IL 60602

Refreshments will be served prior to the meeting.

Please RSVP by calling
(800) 922-6769

( Not able to make it but interested in hearing from your portfolio managers?

This year you can call to listen to an audio recording of the meeting. The recording will be available by 3 p.m. Central Standard Time on September 26 and can be accessed by visiting columbiafunds.com. The recording will be available for approximately two weeks.

Go to columbiafunds.com for the toll free dial in number and pass code.

8Questions? Email Us!

Email questions to:
dg.227w-meeting_questions@bankofamerica.com

For directions and parking information, see the inside back cover of this report.

Columbia Acorn Family of Funds Semiannual Report 2006

Table of Contents

Columbia Acorn Family of Funds

Net Asset Value Per Share					2

2006 Mid-Year Distributions					2

Share Class Performance					3

Fund Performance vs. Benchmarks					4

Squirrel Chatter II: Understanding our Team Approach					5

Understanding Your Expenses					8

Columbia Acorn Fund

In a Nutshell					10

At a Glance					11

Major Portfolio Changes					22

Statement of Investments					24

Columbia Acorn International

In a Nutshell					12

At a Glance					13

Major Portfolio Changes					36

Statement of Investments					38

Portfolio Diversification					43

Columbia Acorn USA

In a Nutshell					14

At a Glance					15

Major Portfolio Changes					44

Statement of Investments					45

Columbia Acorn International Select

In a Nutshell					16

At a Glance					17

Major Portfolio Changes					51

Statement of Investments					52

Portfolio Diversification					55

Columbia Acorn Select

In a Nutshell					18

At a Glance					19

Major Portfolio Changes					56

Statement of Investments					57

Columbia Thermostat Fund

In a Nutshell					20

At a Glance					21

Statement of Investments					80

Statement of Assets and Liabilities					81

Statement of Operations					82

Statement of Changes in Net Assets					83

Financial Highlights					85

Notes to Financial Statements					86

Columbia Acorn Family of Funds

Statements of Assets and Liabilities					62

Statements of Operations					63

Statements of Changes in Net Assets					64

Financial Highlights					68

Notes to Financial Statements					73

Management Fee Evaluation of the Senior Officer					90

Columbia Acorn Family of Funds Information					95

Columbia Acorn Family of Funds

>Net Asset Value Per Share as of 6/30/06

	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn International Select		Columbia Acorn Select		Columbia Thermostat Fund
Class A	$	28.81	$	37.33	$	26.96	$	22.95	$	23.55	$	12.53
Class B	$	27.71	$	36.65	$	25.95	$	22.24	$	22.69	$	12.53
Class C	$	27.66	$	36.61	$	25.92	$	22.23	$	22.66	$	12.52

>2006 Mid-Year Distributions

The following table details the Funds' mid-year distributions. The record date was June 5, 2006. The ex-dividend date was June 6, 2006 and the payable date was June 7, 2006.

	Short-term Capital Gains		Long-term Capital Gains		Ordinary Income		Reinvestment Price
Columbia Acorn Fund Class A, B and C		None	$	0.3132		None		$28.58 A $27.49 B $27.45 C
Columbia Acorn International Class A, B and C		None	$	0.5514		None		$37.19 A $36.52 B $36.48 C
Columbia Acorn USA Class A, B and C		None	$	0.1016		None		$26.84 A $25.85 B $25.82 C
Columbia Acorn International Select Class A (Class B and C had no distributions)		None		None	$	0.0031	$	22.89	A
Columbia Acorn Select Class A	$	0.0862		None	$	0.0235	$	23.41	A
Columbia Acorn Select Class B and C	$	0.0862		None		None		$22.56 B $22.53 C
Columbia Thermostat Fund Class A	$	0.0046	$	0.2367	$	0.0139	$	12.48	A
Columbia Thermostat Fund Class B and C	$	0.0046	$	0.2367		None		$12.48 B $12.47 C

1-800-922-6769

Columbia Acorn Family of Funds

>Share Class Performance Average Annual Total Returns through 6/30/06

	Class A						Class B						Class C
	Without Sales Charge			With Sales Charge			Without Sales Charge			With Sales Charge			Without Sales Charge			With Sales Charge
Columbia Acorn Fund (10/16/2000)
3 months*		-3.81	%		-9.34	%		-3.96	%		-8.70	%		-4.00	%		-4.95	%
Year to date*		5.64	%		-0.43			5.32	%		0.32	%		5.25	%		4.25	%
1 year		16.11	%		9.43	%		15.31	%		10.31	%		15.20	%		14.20	%
3 years		21.49	%		19.11	%		20.64	%		19.95	%		20.57	%		20.57	%
5 years		11.81	%		10.49	%		11.05	%		10.79	%		11.01	%		11.01	%
Life of Fund		13.30	%		12.13	%		12.55	%		12.45	%		12.52	%		12.52	%
Columbia Acorn International (10/16/2000)
3 months*		-1.16	%		-6.85	%		-1.34	%		-6.20	%		-1.34	%		-2.32	%
Year to date*		14.11	%		7.55	%		13.74	%		8.74	%		13.72	%		12.72	%
1 year		34.74	%		26.99	%		33.83	%		28.83	%		33.73	%		32.73	%
3 years		32.29	%		29.70	%		31.38	%		30.80	%		31.35	%		31.35	%
5 years		14.90	%		13.55	%		14.11	%		13.87	%		14.10	%		14.10	%
Life of Fund		9.00	%		7.87	%		8.27	%		8.15	%		8.25	%		8.25	%
Columbia Acorn USA (10/16/2000)
3 months*		-4.44	%		-9.94	%		-4.61	%		-9.36	%		-4.61	%		-5.56	%
Year to date*		2.04	%		-3.82	%		1.73	%		-3.27	%		1.69	%		0.69	%
1 year		9.12	%		2.84	%		8.38	%		3.38	%		8.30	%		7.30	%
3 years		19.07	%		16.74	%		18.24	%		17.53	%		18.20	%		18.20	%
5 years		9.07	%		7.79	%		8.34	%		8.05	%		8.31	%		8.31	%
Life of Fund		13.77	%		12.60	%		13.03	%		12.93	%		13.01	%		13.01	%
Columbia Acorn International Select (10/16/2000)
3 months*		0.41	%		-5.37	%		0.23	%		-4.77	%		0.23	%		-0.77	%
Year to date*		12.74	%		6.25	%		12.32	%		7.32	%		12.27	%		11.27	%
1 year		29.75	%		22.29	%		28.93	%		23.93	%		28.79	%		27.79	%
3 years		27.48	%		24.99	%		26.63	%		26.01	%		26.51	%		26.51	%
5 years		11.46	%		10.14	%		10.73	%		10.46	%		10.69	%		10.69	%
Life of Fund		5.04	%		3.96	%		4.33	%		4.19	%		4.31	%		4.31	%
Columbia Acorn Select (10/16/2000)
3 months*		-2.27	%		-7.89	%		-2.41	%		-7.27	%		-2.46	%		-3.43	%
Year to date*		5.30	%		-0.76	%		4.91	%		-0.09	%		4.87	%		3.87	%
1 year		16.96	%		10.24	%		16.14	%		11.14	%		16.04	%		15.04	%
3 years		15.51	%		13.25	%		14.67	%		13.91	%		14.62	%		14.62	%
5 years		11.34	%		10.03	%		10.56	%		10.30	%		10.55	%		10.55	%
Life of Fund		11.71	%		10.56	%		10.95	%		10.84	%		10.92	%		10.92	%
Columbia Thermostat Fund (3/3/2003)†
3 months*		-0.65	%		-6.36	%		-0.76	%		-5.63	%		-0.84	%		-1.81	%
Year to date*		2.37	%		-3.51	%		2.10	%		-2.90	%		2.02	%		1.02	%
1 year		6.29	%		0.18	%		5.71	%		0.90	%		5.55	%		4.59	%
3 years		8.77	%		6.64	%		8.10	%		7.24	%		8.00	%		8.00	%
Life of Fund		11.66	%		9.70	%		10.96	%		10.25	%		10.87	%		10.87	%

*Not annualized.

Performance data quoted represents past performance and current performance may be lower or higher. Past performance is no guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Please visit www.columbiafunds.com for daily and most recent month-end performance updates.

The "with sales charge" returns include the maximum 5.75% sales charge for Class A shares, the appropriate Class B contingent deferred sales charge for the holding period after purchase as follows: through first year—5%, second year—4%, third year—3%, fourth year—3%, fifth year—2%, sixth year—1%, thereafter—0%; and the Class C contingent deferred sales charge of 1% for the first year only. Performance of the different share classes will vary based on differences in sales charges and fees associated with each class.

Performance results reflect any voluntary waivers or reimbursements of Fund expenses by the Adviser or its affiliates. Absent these waivers or reimbursement arrangements, performance results would have been lower.

Columbia Acorn Family of Funds

>Fund Performance vs. Benchmarks Class A Shares, without sales charge,
Average Annual Total Returns through 6/30/06

	2nd Quarter*			Year to date*			1 year			3 years			5 years			Life of Fund
Columbia Acorn Fund (10/16/00)		-3.81	%		5.64	%		16.11	%		21.49	%		11.81	%		13.30	%
Russell 2500		-4.34	%		6.32	%		13.53	%		19.16	%		9.65	%		9.75	%
S&P 500		-1.44	%		2.71	%		8.63	%		11.22	%		2.49	%		0.29	%
Lipper Small-Cap Core Funds Index		-4.76	%		6.30	%		14.52	%		18.59	%		9.13	%		9.59	%
Lipper Mid-Cap Core Funds Index		-3.29	%		4.31	%		12.07	%		16.41	%		7.25	%		6.12	%
Columbia Acorn International (10/16/00)		-1.16	%		14.11	%		34.74	%		32.29	%		14.90	%		9.00	%
S&P/Citigroup EMI Global ex-US		-1.70	%		10.57	%		31.22	%		31.90	%		18.28	%		14.17	%
MSCI EAFE		0.70	%		10.16	%		26.56	%		23.94	%		10.02	%		5.97	%
Lipper Int'l Small-Cap Funds Index		-2.72	%		10.26	%		31.71	%		32.29	%		17.72	%		12.91	%
Columbia Acorn USA (10/16/00)		-4.44	%		2.04	%		9.12	%		19.07	%		9.07	%		13.77	%
Russell 2000		-5.02	%		8.21	%		14.58	%		18.70	%		8.50	%		8.84	%
Lipper Small-Cap Core Funds Index		-4.76	%		6.30	%		14.52	%		18.59	%		9.13	%		9.59	%
S&P 500		-1.44	%		2.71	%		8.63	%		11.22	%		2.49	%		0.29	%
Columbia Acorn Int'l Select (10/16/00)		0.41	%		12.74	%		29.75	%		27.48	%		11.46	%		5.04	%
S&P/Citigroup World ex-US Cap Range $2-10B		-0.61	%		10.29	%		31.69	%		30.15	%		15.80	%		12.62	%
MSCI EAFE		0.70	%		10.16	%		26.56	%		23.94	%		10.02	%		5.97	%
Lipper International Funds Index		-0.52	%		9.30	%		27.26	%		23.15	%		10.14	%		6.45	%
Columbia Acorn Select (10/16/00)		-2.27	%		5.30	%		16.96	%		15.51	%		11.34	%		11.71	%
S&P MidCap 400		-3.14	%		4.24	%		12.98	%		18.14	%		9.30	%		8.90	%
Lipper Mid-Cap Growth Index		-4.64	%		4.40	%		15.46	%		15.12	%		2.64	%		-2.66	%
S&P 500		-1.44	%		2.71	%		8.63	%		11.22	%		2.49	%		0.29	%
Columbia Thermostat Fund (3/3/03)^†		-0.65	%		2.37	%		6.29	%		8.77	%		—			11.66	%
S&P 500		-1.44	%		2.71	%		8.63	%		11.22	%		—			15.20	%
Lehman Brothers U.S. Credit Intermediate Bond Index		0.06	%		-0.47	%		-0.61	%		1.83	%		—			2.92	%
Lipper Flexible Portfolio Funds Index		-1.30	%		3.07	%		10.01	%		10.40	%		—			13.33	%

*Not annualized.

Description of indexes: S&P 500 is a broad, market-weighted average of U.S. blue-chip company stock performance. S&P MidCap 400 is a broad market-weighted index of 400 stocks that are in the next size/tier down from the S&P 500. Russell 2000 is a market-weighted index of 2000 smaller U.S. companies, formed by taking the largest 3,000 companies and eliminating the largest 1,000. Russell 2500 is the smallest 2,500 U.S. companies from this same group. S&P/Citigroup EMI Global ex-US is the bottom 20% of institutionally investable capital of developed and emerging countries, selected by the index sponsor, outside the U.S. MSCI EAFE is Morgan Stanley's Europe, Australasia and Far East Index, a widely recognized international benchmark that comprises 20 major markets in proportion to world stock market capitalization. S&P/Citigroup World ex-US Cap Range $2–10B is a subset of the broad market selected by the index sponsor representing the mid-cap developed market excluding the U.S. Lipper Indexes include the largest funds tracked by Lipper, Inc. in the named category. Lipper Mid-Cap Growth Index, 30 mid-cap growth funds; Lipper Mid-Cap Core Funds Index, 30 mid-cap core funds; Lipper International Funds Index, 30 largest non-U.S. funds, not including non-U.S. small-cap funds; Lipper International Small-Cap Funds Index, 10 largest non-U.S. funds investing in small-cap companies, including Columbia Acorn International; Lipper Small-Cap Core Funds Index, 30 largest small-cap core funds, including Columbia Acorn Fund. Lipper Flexible Portfolio Funds Index is an equal dollarweighted index of the 30 largest mutual funds within the Flexible Portfolio fund classification, as defined by Lipper. The Lehman Brothers U.S. Credit Intermediate Bond Index is the intermediate component of the U.S. Credit Index. The U.S. Credit Index includes publicly issued U.S. corporate and foreign debentures and secured notes that meet specified maturity, liquidity, and quality requirements. All indexes are unmanaged and returns include reinvested distributions. It is not possible to invest directly in an index.

1-800-922-6769

>Squirrel Chatter II: Understanding our Team Approach

In recent Squirrel Chatters, I've discussed the performance drivers of the Columbia Acorn Funds. First, I addressed our style—investing in small- and mid-cap stocks using a Growth-at-a-Reasonable-Price discipline. Next, I covered our analytical process—how we research, value and track our investments. In this final part of the series, I cover why we need a large analyst team, how we hire and train analysts, and how we empower and evaluate them.

A Large Team Provides Full Market Coverage

Hiring Good Analysts

the street. If parking lots are raising their rates, or if a restaurant chain has people lined up out the door, a true stock nut will see these as possible investment opportunities.

Mentoring New Analysts

As a new analyst begins to cover inherited stocks, the mentor has him or her pursue the information, valuation and time horizon edges that we discussed last quarter. The two analysts may conduct a few management meetings and attend a few conferences together so that they can compare notes and the mentor can help the new analyst adopt our process and style.

Empowering and Evaluating Analysts

Due to the size of our flagship funds,² the quality of our analysts, our desire for accountability, and our belief that our analysts understand their stocks better than our portfolio managers do, Columbia Acorn Fund and Columbia Acorn International senior analysts have authority to buy and sell individual stocks. Portfolio managers and mentors provide quick approval for reasonable transactions proposed by newer analysts. Portfolio managers also make strategic decisions, including industry and country weightings.

1-800-922-6769

CWAM News

Charles P. McQuaid

President and Chief Investment Officer
Columbia Wanger Asset Management, L.P.

Past performance is no guarantee of future results.

Stocks of small- and mid-cap companies pose special risks, including possible illiquidity and greater price volatility than stocks of larger, more established companies.

¹ Our understanding of the competing small-cap analyst team size is based on conversations we have had with competitors and information provided by third-parties who report on the fund industry.

² As of June 30, 2006, Columbia Acorn Fund had $17.9 billion in total net assets. It owned 415 stocks, 334 domestic and 81 foreign. Columbia Acorn International had $3.6 billion and invested in 173 stocks.

>Understanding Your Expenses

Analyzing your Fund's expenses

To illustrate these ongoing costs, we have provided examples and calculated the expenses paid by investors in the Class A, B and C shares of the Columbia Acorn Funds for the last six months. The information in the following table is based on an initial investment of $1,000, which is invested at the beginning of the period and held for the entire period. Expense information is calculated two ways and each method provides you with different information. The amount listed in the "Actual" column is calculated using each Fund's actual operating expenses and total return for the period. The amount listed in the "Hypothetical" column assumes that the return each year is 5% before expenses and then applies each Fund's actual expense ratio for the period to the hypothetical return. You should not use the hypothetical account values and expenses to estimate either your actual account balance at the end of the period or the expenses you paid during the reporting period. See the "Compare with other funds" information for details on using the hypothetical data.

Compare with other funds

Estimating your actual expenses

To estimate the expenses that you paid over the period, first you will need your account balance at the end of the period:

• For shareholders who receive their account statements from their brokerage firm, contact your brokerage firm to obtain your account balance.

1. Divide your ending account balance by $1,000. For example, if an account balance was $8,600 at the end of the period, the result would be 8.6.

1-800-922-6769

>January 1, 2006 – June 30, 2006

	Account value at the beginning of the period ($)				Account value at the end of the period ($)				Expenses paid during the period ($)				Fund's annualized expense
	Actual		Hypothetical		Actual		Hypothetical		Actual		Hypothetical		ratio (%)*
Columbia Acorn Fund
Class A		1,000.00		1,000.00		1,056.43		1,019.79		5.15		5.06		1.01
Class B		1,000.00		1,000.00		1,053.21		1,016.36		8.65		8.50		1.70
Class C		1,000.00		1,000.00		1,052.51		1,015.87		9.16		9.00		1.80
Columbia Acorn International
Class A		1,000.00		1,000.00		1,141.08		1,018.74		6.48		6.11		1.22
Class B		1,000.00		1,000.00		1,137.36		1,015.22		10.23		9.64		1.93
Class C		1,000.00		1,000.00		1,137.21		1,014.88		10.60		9.99		2.00
Columbia Acorn USA
Class A		1,000.00		1,000.00		1,020.43		1,018.60		6.26		6.26		1.25
Class B		1,000.00		1,000.00		1,017.26		1,015.08		9.80		9.79		1.96
Class C		1,000.00		1,000.00		1,016.86		1,014.63		10.25		10.24		2.05
Columbia Acorn International Select
Class A		1,000.00		1,000.00		1,127.34		1,016.86		8.44		8.00		1.60
Class B		1,000.00		1,000.00		1,123.23		1,013.44		12.06		11.43		2.29
Class C		1,000.00		1,000.00		1,122.73		1,012.89		12.63		11.98		2.40
Columbia Acorn Select
Class A		1,000.00		1,000.00		1,052.96		1,018.70		6.26		6.16		1.23
Class B		1,000.00		1,000.00		1,049.14		1,015.12		9.91		9.74		1.95
Class C		1,000.00		1,000.00		1,048.70		1,014.68		10.36		10.19		2.04
Columbia Thermostat Fund
Class A		1,000.00		1,000.00		1,023.70		1,022.32		2.51		2.51		0.50
Class B		1,000.00		1,000.00		1,020.98		1,019.34		5.51		5.51		1.10
Class C		1,000.00		1,000.00		1,020.18		1,018.60		6.26		6.26		1.25

Had the Investment Adviser and/or Transfer Agent not reimbursed/waived a portion of expenses, total return would have been reduced.

Columbia Thermostat Fund's expenses do not include fees and expenses incurred by the Fund from the underlying portfolio funds.

*For the six months ended June 30, 2006.

Columbia Acorn Fund

>In a Nutshell

Visit columbiafunds.com for daily and most recent month-end performance updates.

Columbia Acorn Fund fell 3.81% (Class A shares, without sales charge) in the second quarter, modestly outperforming the small-cap Russell 2500 Index while underperforming the large-cap S&P 500 Index. In the first half of 2006, Columbia Acorn Fund rose 5.64%, slightly less than the Russell 2500 and somewhat more than the S&P 500.

Expeditors International of Washington, Columbia Acorn Fund's largest dollar winner in the first quarter, kept that distinction in the second quarter, delivering another 30% gain. Other winners included takeovers—12 Columbia Acorn stocks put themselves up for sale and announced deals in the quarter! Six takeovers wound up within the top dozen percentage performers for the quarter, including software firm RSA Security and Canadian mining company Falconbridge, each surging over 50%. Sweden's Gambro and Georgia-based Serologicals, both medical products companies, jumped about 30% each. Aerospace components distributor Aviall and natural gas producer Western Gas Resources rounded out the takeover winner's circle, each rising nearly 25%.

Columbia Acorn Fund's foreign stocks have performed spectacularly well since we decided to increase their weighting three years ago—up 174% vs. a 79% gain for the overall Fund.¹ We reviewed all of the Fund's foreign holdings during the period in an attempt to be more selective. We believe that many foreign stocks continue to appear cheaper than U.S. stocks, while others may not have enough upside to compensate for possible risks. Consequently, we cut the Fund's foreign stock weighting slightly, to 13.7%.

Charles P. McQuaid

Lead Portfolio Manager

Robert A. Mohn

Co-Portfolio Manager

1-800-922-6769

Columbia Acorn Fund (LACAX)

>At a Glance

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

>through June 30, 2006

Inception 10/16/00		Year to date*		1 year		5 years		Life of fund
Returns before taxes	NAV POP	5.64% -0.43		16.11% 9.43		11.81% 10.49		13.30% 12.13
Returns after taxes on distributions	NAV POP	5.47 -0.59		15.17 8.55		11.43 10.12		12.45 11.29
Returns after taxes on distributions and sale of fund shares	NAV POP	3.89 -0.07		11.65 7.24		10.28 9.10		11.36 10.31
Russell 2500 (pretax)			6.32		13.53		9.65		9.75
S&P 500 (pretax)			2.71		8.63		2.49		0.29

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the tax impact of gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes. Investment returns and principal value may fluctuate, resulting in a gain or loss on sale.

Public offering price (POP) returns include the maximum sales charge of 5.75% for Class A shares. Net asset value (NAV) returns do not include sales charges or contingent deferred sales charges (CDSC).

*Year-to-date data not annualized.

Columbia Acorn Fund Portfolio Diversification

>as a % of net assets, as of June 30, 2006

The Growth of a $75,000 Investment in Columbia Acorn Fund (Class A)

>October 16, 2000 through June 30, 2006

Illustration is based on a hypothetical $75,000 investment from inception in Class A shares of the Fund, which includes the 4.50% maximum initial sales charge for this level of investment. The Russell 2500 is the smallest 2,500 U.S. companies taken from a group of the largest 3,000 companies. The index is unmanaged and returns for the index and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index.

Performance may reflect any voluntary waiver or reimbursement of Fund expenses by the Adviser or its affiliates. Absent these waivers or reimbursement arrangements, performance results would have been lower.

Total Net Assets of the Fund: $17,916.1 million

Columbia Acorn Fund Top 10 Holdings (as a % of net assets)

1. Expeditors International of Washington International Freight Forwarder	1.7	%
2. Coach Designer & Retailer of Branded Leather Accessories	1.2	%
3. Western Gas Resources Oil & Coal Seam Gas Producer	1.1	%
4. AmeriCredit Auto Lending	1.0	%
5. Chico's FAS Women's Specialty Retail	0.9	%
6. Ultra Petroleum Natural Gas Producer	0.9	%
7. FMC Technologies Oil & Gas Well Head Manufacturer	0.9	%
8. Crown Castle International Communications Towers	0.9	%
9. ITT Educational Services Post-secondary Degree Programs	0.8	%
10. Peoples Bank Bridgeport Connecticut Savings & Loan	0.8	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

Columbia Acorn International

>In a Nutshell

Visit columbiafunds.com for daily and most recent month-end performance updates.

Columbia Acorn International ended the quarter down 1.16% (Class A shares, without sales charge) vs. a 1.70% decline for the benchmark S&P/Citigroup EMI Global ex-US Index. Year-to-date through June 30, the Fund was up 14.11%, well ahead of the 10.57% gain of the index. The Fund's half year return also easily topped the 10.16% return of the large-cap oriented MSCI EAFE Index.

P. Zachary Egan

Co-Portfolio Manager

Louis J. Mendes III

Co-Portfolio Manager

1-800-922-6769

Columbia Acorn International (LAIAX)

>At a Glance

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

>through June 30, 2006

Inception 10/16/00		Year to date*		1 year		5 years		Life of fund
Returns before taxes	NAV POP	14.11% 7.55		34.74% 26.99		14.90% 13.55		9.00% 7.87
Returns after taxes on distributions	NAV POP	13.86 7.31		33.85 26.15		14.74 13.38		8.30 7.19
Returns after taxes on distributions and sale of fund shares	NAV POP	9.50 5.22		23.93 18.82		13.15 11.93		7.59 6.60
S&P/Citigroup EMI Global ex-US (pretax)			10.57		31.22		18.28		14.17

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the tax impact of gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. The return after taxes on distributions may be higher than the return before taxes due to qualified foreign tax credits. Indexes do not reflect any deduction for fees, expenses or taxes. Investment returns and principal value may fluctuate, resulting in a gain or loss on sale.

*Year-to-date data not annualized.

Columbia Acorn International Portfolio Diversification

>as a % of net assets, as of June 30, 2006

The Growth of a $10,000 Investment in Columbia Acorn International (Class A)

>October 16, 2000 through June 30, 2006

Illustration is based on a hypothetical $10,000 investment from inception in Class A shares of the Fund, which includes the 5.75% maximum initial sales charge. The S&P/Citigroup EMI Global ex-US is Citigroup's index of the bottom 20% of institutionally investable capital of developed and emerging countries, as selected by Citigroup, excluding the U.S. The index is unmanaged and returns for both the index and Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index.

Total Net Assets of the Fund: $3,596.3 million

Columbia Acorn International Top 10 Holdings (as a % of net assets)

1. Hexagon (Sweden) Measurement Equipment & Polymers	1.6	%
2. Fugro (Netherlands) Survey & GPS Services	1.5	%
3. USG People (Netherlands) Temporary Staffing Services	1.4	%
4. Tullow Oil (United Kingdom) Oil & Gas Producer	1.3	%
5. Aalberts Industries (Netherlands) Flow Control & Heat Treatment	1.1	%
6. Rhoen-Klinikum (Germany) Health Care Services	1.1	%
7. April Group (France) Insurance Policy Construction	1.0	%
8. Bank of Ireland (Ireland) Irish Commercial Bank	1.0	%
9. IAWS Group (Ireland) Baked Goods	1.0	%
10. Wincor Nixdorf (Germany) Retail POS Systems & ATM Machines	1.0	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

Columbia Acorn USA

>In a Nutshell

Visit columbiafunds.com for daily and most recent month-end performance updates.

After a first quarter surge, small caps pulled back in the second quarter. Columbia Acorn USA ended the second quarter down 4.44% (Class A shares, without sales charge) vs. a 5.02% decline for the Russell 2000. First quarter underperformance dampened returns for the six-month period. Year-to-date through June 30, the Fund was up 2.04% vs. an 8.21% gain for the benchmark.

On the downside, Neurocrine Biosciences' stock collapsed when the FDA withheld full approval for the high dosage of its sleep medication Indiplon. The Fund sold out of the stock, taking a 66% blow for the quarter and 65% loss for the six months. Interestingly enough, Neurocrine stock fell a further 50% after we got out. As mentioned, several retail names were down in the Fund. Oxford Industries, a maker of branded and private label apparel, fell 23% in the quarter and was off 28% for the six months on disappointing sales in its menswear lines. Chico's FAS, a women's specialty retailer, fell more than 34% in the quarter and 40% in the half year as new merchandise failed to move and sales came in short.

Robert A. Mohn

Lead Portfolio Manager

1-800-922-6769

Columbia Acorn USA (LAUAX)

>At a Glance

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

>through June 30, 2006

Inception 10/16/00		Year to date*		1 year		5 years		Life of fund
Returns before taxes	NAV POP	2.04% -3.82		9.12% 2.84		9.07% 7.79		13.77% 12.60
Returns after taxes on distributions	NAV POP	1.99 -3.88		8.46 2.23		8.83 7.55		13.55 12.38
Returns after taxes on distributions and sale of fund shares	NAV POP	1.41 -2.41		6.79 2.66		7.86 6.73		12.13 11.06
Russell 2000 (pretax)			8.21		14.58		8.50		8.84

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the tax impact of gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes. Investment returns and principal value may fluctuate, resulting in a gain or loss on sale.

*Year-to-date data not annualized.

Columbia Acorn USA Portfolio Diversification

>as a % of net assets, as of June 30, 2006

The Growth of a $75,000 Investment in Columbia Acorn USA (Class A)

>October 16, 2000 through June 30, 2006

Illustration is based on a hypothetical $75,000 investment from inception in Class A shares of the Fund, which includes the 4.50% maximum initial sales charge for this level of investment. The Russell 2000 is a market-weighted index of 2,000 smaller U.S. companies formed by taking the largest 3,000 U.S. companies and eliminating the largest 1,000. The index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index.

Total Net Assets of the Fund: $1,470.3 million

Columbia Acorn USA Top 10 Holdings (as a % of net assets)

1. Crown Castle International Communication Towers	2.4	%
2. AmeriCredit Auto Lending	2.1	%
3. Esco Technologies Automatic Electric Meter Readers	2.1	%
4. ITT Educational Services Post-secondary Degree Programs	1.9	%
5. Genlyte Group Commercial Lighting Fixtures	1.9	%
6. FMC Technologies Oil & Gas Well Head Manufacturer	1.8	%
7. Edwards Lifesciences Heart Valves	1.8	%
8. Avid Technology Digital Nonlinear Editing Software & Systems	1.8	%
9. Oxford Industries Branded & Private Label Apparel	1.7	%
10. Kronos Labor Management Solutions	1.6	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

Columbia Acorn International Select

>In a Nutshell

Visit columbiafunds.com for daily and most recent month-end performance updates.

Columbia Acorn International Select ended the second quarter up 0.41% (Class A shares, without sales charge), outperforming the 0.61% drop of S&P/Citigroup World ex-US Cap Range $2-10B Index. Year-to-date through June 30, the Fund was up 12.74%, well ahead of the 10.29% return of the index.

Christopher J. Olson

Lead Portfolio Manager

1-800-922-6769

Columbia Acorn International Select (LAFAX)

>At a Glance

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

>through June 30, 2006

Inception 10/16/00		Year to date*		1 year		5 years		Life of fund
Returns before taxes	NAV POP	12.74% 6.25		29.75% 22.29		11.46% 10.14		5.04% 3.96
Returns after taxes on distributions	NAV POP	12.73 6.25		29.89 22.43		11.49 10.18		5.04 3.96
Returns after taxes on distributions and sale of fund shares	NAV POP	8.28 4.07		19.48 14.62		10.09 8.92		4.40 3.45
S&P/Citigroup World ex-US Cap Range $2-10B (pretax)			10.29		31.69		15.80		12.62

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the tax impact of gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. The return after taxes on distributions may be higher than the return before taxes due to qualified foreign tax credits. Indexes do not reflect any deduction for fees, expenses or taxes. Investment returns and principal value may fluctuate, resulting in a gain or loss on sale.

*Year to date data not annualized.

Columbia Acorn International Select Portfolio Diversification

>as a % of net assets, as of June 30, 2006

The Growth of a $10,000 Investment in Columbia Acorn International Select (Class A)

>October 16, 2000 through June 30, 2006

Illustration is based on a hypothetical $10,000 investment from inception in Class A shares of the Fund, which includes the 5.75% maximum initial sales charge. S&P/Citigroup World ex-US Cap Range $2-10B Index is a subset of Citigroup's Broad Market Index, representing a mid-cap developed market index excluding the U.S. The index and Fund returns include reinvested dividends and capital gains. It is not possible to invest directly in an index.

Total Net Assets of the Fund: $119.2 million

Columbia Acorn International Select Top 10 Holdings (as a % of net assets)

1. Bank of Ireland (Ireland) Irish Commercial Bank	4.2	%
2. C&C Group (Ireland) Beverage Company	3.6	%
3. Daito Trust Construction (Japan) Apartment Builder	3.5	%
4. Anglo Irish Bank (Ireland) Small Business & Middle Market Banking	3.5	%
5. Northern Rock (United Kingdom) Lowest Cost Mortgage Bank in UK	3.3	%
6. Hoya (Japan) Opto-Electrical Components & Eyeglass Lenses	3.3	%
7. Hong Kong Exchanges and Clearing (Hong Kong) Hong Kong Equity & Derivatives Market Operator	3.3	%
8. IAWS Group (Ireland) Baked Goods	3.3	%
9. Jupiter Telecommunications (Japan) Largest Cable Service Provider in Japan	3.1	%
10. Synthes (Switzerland) Products for Orthopedic Surgery	3.0	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

Columbia Acorn Select

>In a Nutshell

Visit columbiafunds.com for daily and most recent month-end performance updates.

Columbia Acorn Select was down 2.27% (Class A shares, without sales charge) in the second quarter vs. a 3.14% decline of the S&P MidCap 400 Index. Year-to-date through June 30, the Fund was up 5.30%, 1.06% greater than its S&P MidCap 400 benchmark and 2.59% greater than the S&P 500's year-to-date gain of 2.71%.

Ben Andrews

Lead Portfolio Manager

1-800-922-6769

Columbia Acorn Select (LTFAX)

>At a Glance

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

>through June 30, 2006

Inception 10/16/00		Year to date*		1 year		5 years		Life of fund
Returns before taxes	NAV POP	5.30% -0.76		16.96% 10.24		11.34% 10.03		11.71% 10.56
Returns after taxes on distributions	NAV POP	5.13 -0.92		16.39 9.70		11.11 9.81		11.46 10.31
Returns after taxes on distributions and sale of fund shares	NAV POP	3.44 -0.49		11.50 7.10		9.86 8.69		10.21 9.18
S&P MidCap 400 (pretax)			4.24		12.98		9.30		8.90

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the tax impact of gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes. Investment returns and principal value may fluctuate, resulting in a gain or loss on sale.

*Year-to-date data not annualized.

Columbia Acorn Select Portfolio Diversification

>as a % of net assets, as of June 30, 2006

The Growth of a $50,000 Investment in Columbia Acorn Select (Class A)

>October 16, 2000 through June 30, 2006

Illustration is based on a hypothetical $50,000 investment from inception in Class A shares of the Fund, which includes the 4.50% maximum initial sales charge for this level of investment. The S&P MidCap 400 is a broad, market-weighted index of 400 stocks that are in the next size/tier down from the S&P 500. The Index is unmanaged and returns for both the index and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index.

Total Net Assets of the Fund: $1,937.7 million

Columbia Acorn Select Top 10 Holdings (as a % of net assets)

1. Tellabs Telecommunications Equipment	6.7	%
2. ITT Educational Services Post-secondary Degree Programs	5.5	%
3. Liberty Global CATV Holding Company	4.7	%
4. Safeway Supermarkets	4.7	%
5. UrAsia Energy (Canada) Uranium Mining in Kazakhstan	4.1	%
6. Abercrombie & Fitch Teen Apparel Retailer	4.0	%
7. Expeditors International of Washington International Freight Forwarder	3.8	%
8. American Tower Communication Towers in USA & Mexico	3.7	%
9. Pride International Contract Drilling	3.1	%
10. Harley-Davidson Motorcycles & Related Merchandise	3.1	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

Columbia Thermostat Fund

>In a Nutshell

Visit columbiafunds.com for daily and most recent month-end performance updates.

Columbia Thermostat Fund ended the second quarter down 0.65% (Class A shares, without sales charge). This compares to a 1.44% decline for the S&P 500 and a 0.06% gain for the Lehman Brothers U.S. Credit Intermediate Bond Index. The Lipper Flexible Portfolio Funds Index fell 1.30% for the three-month period. For the half year, the Fund was up 2.37% vs. 2.71% for the S&P 500, a 0.47% decline for the Lehman Brothers U.S. Credit Intermediate Bond Index and a 3.07% gain for the Lipper Flexible Portfolio Funds Index.

The Fund hit two reallocation triggers in the second quarter. In April the stock component was raised 5% to 45% of the portfolio. In June the weighting was raised again to 50% stocks, 50% bonds.

So far 2006 has been the type of investment environment for which Columbia Thermostat Fund was made. Thank you for your investment in the Fund.

Charles P. McQuaid

Lead Portfolio Manager

Results of the Funds Owned in Columbia Thermostat Fund at June 30, 2006

Equities

Fund	Weightings in Category			2nd quarter returns			6-month returns to 6/30/06
Columbia Acorn Fund Z		15	%		-3.73	%		5.81	%
Columbia Acorn Select Z		10	%		-2.22	%		5.43	%
Columbia Large Cap Value Fund		15	%		-0.57	%		5.45	%
Columbia Acorn International Z		15	%		-1.11	%		14.27	%
Columbia Dividend Income Fund		20	%		0.48	%		4.07	%
Columbia Large Cap Enhanced Core Fund		25	%		-2.15	%		2.40	%
*Weighted Average* *Equity Return*		*100*	%		*-1.45*	%		*5.79*	%

Fixed Income

Fund	Weightings in Category			2nd quarter returns			6-month return to 6/30/06
Columbia Federal Securities Fund		30	%		-0.26	%		-1.13	%
Columbia Intermediate Bond Fund		50	%		-0.22	%		-0.71	%
Columbia Conservative High Yield Fund		20	%		-1.70	%		-0.42	%
*Weighted Average* *Income Return*		*100*	%		*-0.53*	%		*-0.78*	%

Columbia Thermostat Fund Rebalancing in the Second Quarter

April 17, 2006:				45% stock, 55% bond
June 13, 2006:				50% stock, 50% bond

1-800-922-6769

Columbia Thermostat Fund (CTFAX)

>At a Glance

Pretax and After-tax Average Annual Total Returns (Based on Class A Share Returns)

>through June 30, 2006

Inception 3/3/03		Year to date*		1 year		3 years		Life of fund
Returns before taxes	NAV POP		2.37% -3.51		6.29% 0.18		8.77% 6.64		11.66% 9.70
Returns after taxes on distributions	NAV POP		2.03 -3.83		4.16 -1.83		7.50 5.40		10.49 8.54
Returns after taxes on distributions and sale of fund shares	NAV POP		1.92 -1.93		5.53 1.47		7.05 5.22		9.63 7.91
S&P 500 (pretax)			2.71		8.63		11.22		15.20
Lehman Brothers U.S. Credit Intermediate Bond Index (pretax)			-0.47		-0.61		1.83		2.92
Lipper Flexible Portfolio Funds Index (pretax)			3.07		10.01		10.40		13.33

After-tax returns are calculated using the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Returns after taxes on distributions and sale of Fund shares reflect the tax impact of gains or losses realized when Fund shares are sold. The returns are taxed at the maximum rate and assume shares were purchased at the beginning of the period. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class A shares only; after-tax returns for other share classes will vary. Indexes do not reflect any deduction for fees, expenses or taxes. Investment returns and principal value may fluctuate, resulting in a gain or loss on sale.

*Year-to-date data not annualized.

Columbia Thermostat Fund Portfolio Weightings

>as a % of assets in each investment category, as of June 30, 2006

The Growth of a $10,000 Investment in Columbia Thermostat Fund (Class A)

>March 3, 2003 through June 30, 2006

Illustration is based on a hypothetical $10,000 investment from inception in Class A shares of the Fund, which includes the 5.75% maximum initial sales charge. The S&P 500 is a broad, market-weighted average of U.S. blue-chip company stock performance. The Lehman Brothers U.S. Credit Intermediate Bond Index is the intermediate component of the U.S. Credit Index. The U.S. Credit Index includes publicly issued U.S. corporate and foreign debentures and secured notes that meet specified maturity, liquidity, and quality requirements. The Lipper Flexible Portfolio Funds Index is an equal dollar weighted index of the 30 largest mutual funds within the Flexible Portfolio fund classification, as defined by Lipper. The Indexes are unmanaged and returns for the indexes and the Fund include reinvested dividends and capital gains. It is not possible to invest directly in an index.

Total Net Assets of the Fund: $191.3 million

Columbia Thermostat Fund Asset Allocation

>as a % of net assets, as of June 30, 2006

Columbia Acorn Fund

>Major Portfolio Changes in the Second Quarter (Unaudited)

	Number of Shares
	03/31/06		06/30/06
Additions
Information
Alliance Atlantis Communication (Canada)		960,000		1,423,100
Amphenol		1,540,000		1,620,000
Avnet		2,300,000		2,550,000
Belden CDT		1,173,000		1,705,000
Ceridian		2,435,000		2,585,000
CNET Networks		3,000,000		4,000,000
Concur Technologies		675,000		1,766,000
EResearch Technology		0		1,050,000
Gemstar-TV Guide International		7,912,000		8,000,000
II VI		1,635,000		1,885,000
Integrated Device Technology		3,060,000		3,390,000
Kenexa		0		160,000
Kronos		2,250,000		2,750,000
Micros Systems		1,425,000		1,800,000
Navigant Consulting		1,836,000		1,900,000
Nice Systems (Israel)		1,434,000		1,634,000
(includes the effect of a 2 for 1 stock split)
Novell		11,500,000		12,000,000
Openwave Systems		0		1,500,000
Proquest Company		0		2,000,000
Radiant Systems		0		1,100,000
Saga Communications		924,000		1,400,000
Sanmina - SCI		0		4,000,000
Supertex		565,000		690,000
Symbol Technologies		2,560,000		4,425,000
Tellabs		9,800,000		10,000,000
THQ		1,050,000		1,700,000
Tumbleweed Communications		1,761,000		3,240,000
ValueClick		2,000,000		3,000,000
webMethods		518,000		1,240,000
Consumer Goods/Services
Abercrombie & Fitch		2,000,000		2,200,000
Borders Group		1,300,000		1,450,000
C&C Group (Ireland)		0		2,500,000
Cavco Industries		55,000		172,000
Champion Enterprises		0		900,000
Chattem		0		750,000
Chico's FAS		5,090,000		5,960,000
Coach		5,980,000		6,980,000
Ducati Motor (Italy)		2,850,000		5,700,000
Expedia		0		3,500,000
Fleetwood Enterprises		4,190,000		4,690,000
Helen of Troy		1,416,000		1,800,000
HNI		2,400,000		2,550,000
Jarden		800,000		1,000,000
J Crew Group		0		1,100,000
Localiza Rent A Car		0		168,800
Pool Corporation		1,820,000		2,190,000
Princeton Review		1,939,000		2,550,000

	Number of Shares
	03/31/06		06/30/06
Consumer Goods/Services—continued
Red Robin Gourmet Burgers		805,000		1,000,000
Rite Aid		7,850,000		8,000,000
Scotts Miracle-Gro		1,790,000		2,620,000
ServiceMaster		0		470,000
Station Casinos		885,000		1,000,000
Thor Industries		201,000		441,000
True Religion Apparel		600,000		700,000
Universal Technical Institute		100,000		1,000,000
Urban Outfitters		2,427,000		3,900,000
Industrial Goods/Services
Donaldson		3,275,000		3,600,000
Drew Industries		730,000		1,048,000
Flir Systems		1,300,000		1,850,000
Florida Rock Industries		1,537,000		1,900,000
Goodman Global		0		1,600,000
K&F Industries Holdings		994,000		1,187,000
Legrand (France)		0		700,000
Martin Marietta		0		605,000
Quanta Services		2,481,000		2,500,000
Simpson Manufacturing		1,450,000		2,200,000
UTI Worldwide		2,700,000		3,000,000
Worthington Industries		1,964,000		2,160,000
W.W. Grainger		0		750,000
Finance
AmeriCredit		6,321,000		6,500,000
Assurant		830,000		1,200,000
Cascade Bancorp		118,000		500,000
Chittenden		756,000		892,000
Delphi Financial Group		250,000		750,000
(includes the effect of a 3 for 2 stock split)
East West Bancorp		0		400,000
Eaton Vance		3,170,000		3,970,000
Electro Rent		361,000		832,000
Great Southern Bancorp		675,000		796,000
Greene County Bancshares		0		150,000
Marlin Business Services		0		263,000
McGrath Rentcorp		550,000		930,000
National Financial		0		600,000
Philadelphia Consolidated Holding		1,725,000		2,040,000
Scottish Re Group		0		1,700,000
West Bancorporation		758,000		886,000
Energy/Minerals
Atwood Oceanics		0		1,000,000
Fugro (Netherlands)		1,235,000		2,728,302
Helmerich & Payne		0		257,000
Hugoton Royalty		0		150,000
Maritrans		0		600,000
Rowan		0		971,000

1-800-922-6769

	Number of Shares
	03/31/06		06/30/06
Additions (continued)
Health Care
LCA Vision		621,000		875,000
Rigel Pharmaceuticals		1,216,000		1,275,000
Tercica		198,000		1,500,000
Other Industries
Gaylord Entertainment		1,400,000		1,560,000
Highland Hospitality		4,825,000		5,850,000
Parkway Properties		400,000		536,000
Sales
Information
Activision		2,000,000		1,000,000
Andrew		1,750,000		1,380,000
CDW		295,000		0
Getty Images		1,200,000		600,000
Hong Kong Exchanges and Clearing (Hong Kong)		9,000,000		6,500,000
International Game Technology		3,840,000		2,750,000
Jabil Circuit		2,275,000		1,705,000
Logitech (Switzerland)		300,000		0
MRO Software		1,000,000		241,000
Novatek Microelectronics (Taiwan)		5,254,000		4,000,000
Plexus		1,961,000		1,570,000
RSA Security		3,000,000		2,500,000
Sybase		1,000,000		0
Consumer Goods/Services
Aeropostale		1,040,000		936,000
Coinstar		1,440,000		0
Columbia Sportswear		400,000		0
IAWS Group (Ireland)		1,900,000		1,597,000
Intrawest (Canada)		1,044,000		900,000
Michaels Stores		3,560,000		2,760,000
Natura Cosmeticos		3,150,000		1,100,000
Park 24 (Japan)		870,000		154,000
Shimano (Japan)		780,000		90,000
Sports Authority		1,520,000		0
Zale		1,072,000		0
Industrial Goods/Services
Administaff		1,300,000		1,100,000
Grafton Group (Ireland)		3,800,000		3,500,000
Kingspan Group (Ireland)		1,250,000		1,000,000
Spartech		3,150,000		2,800,000
Tenaris (Argentina)		1,800,000		1,500,000
(includes the effect of a 5 for 1 stock split)
Tennant		150,000		0
Ultrapar (Brazil)		750,000		438,000
USG People (Netherlands)		740,000		650,000
Vallourec (France)		95,200		33,000
Wienerberger (Austria)		425,000		0

	Number of Shares
	03/31/06		06/30/06
Finance
Anglo Irish Bank (Ireland)		3,600,000		3,500,000
Bankinter (Spain)		200,000		0
Cascade Financial		477,500		0
(includes the effect of a 5 for 4 stock split)
Independent Bank		265,000		0
Investment Technology Group		690,000		350,000
Leucadia National		1,993,000		1,748,000
(includes the effect of a 2 for 1 stock split)
Northgate (United Kingdom)		1,000,000		0
Paragon Group (United Kingdom)		1,950,000		1,120,000
Republic		1,581,000		0
Scottish Re Group		1,700,000		0
Sterling Bancorp		503,000		0
TCF Financial		3,356,000		3,156,000
Energy/Minerals
Chicago Bridge & Iron		1,600,000		1,193,000
Newpark Resources		5,000,000		2,860,000
Pioneer Drilling		168,000		0
Saipem (Italy)		2,000,000		1,200,000
Sociedad Quimica Y Minera de Chile (Chile)		275,000		195,000
Talisman Energy (Canada)		7,500,000		4,900,000
(includes the effect of a 2 for 1 stock split)
Veritas DGC		700,000		350,000
Health Care
Charles River Laboratories		1,595,000		1,355,000
Datascope		1,065,000		455,000
DOV Pharmaceuticals		1,540,000		0
Gambro (Sweden)		4,260,000		0
Incyte		3,935,000		0
Martek Biosciences		650,000		0
Neurocrine Biosciences		913,000		0
Pozen		2,400,000		0
Sybron Dental Specialties		283,000		0
Symmetry Medical		965,000		0
Tanox		685,000		0
United Drug (Ireland)		4,145,810		4,000,000
Other Industries
Comfort Del Gro (Singapore)		18,000,000		0
Grupo Aeroportuario Del Sureste (Mexico)		800,000		760,000
Heartland Express		1,634,000		1,584,000
(includes the effect of a 4 for 3 stock split)

Columbia Acorn Fund

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares			Value (000)
			Common Stocks and Other Equity-Like Securities: 93.8%
Information: 22.8%
		Software/Services
		>Business Software: 3.3%
	2,750,000	Kronos (b)(c)	$	99,577
		Labor Management Solutions
	12,000,000	Novell (b)		79,560
		Directory, Operating System & Identity Management Software
	1,800,000	Micros Systems (b)		78,624
		Information Systems for Restaurants & Hotels
	1,800,000	Avid Technology (b)		59,994
		Digital Nonlinear Editing Software & Systems
	1,800,000	Cadence Design Systems (b)		30,870
		Electronic Design Automation
	1,427,000	Witness Systems (b)		28,783
		Customer Experience Management Software
	1,766,000	Concur Technologies (b)		27,320
		Web Enabled Enterprise Applications
	6,000,000	Actuate (b)(c)		24,240
		Information Delivery Software & Solutions
	1,000,000	Progress Software (b)		23,410
		Application Development Software
	1,490,000	JDA Software (b)(c)		20,905
		Applications/Software & Services for Retailers
	3,000,000	Lawson Software (b)		20,100
		Enterprise Resource Planning (ERP) Software
	928,000	SSA Global Technologies (b)		17,985
		Enterprise Resource Planning (ERP) Software
	5,600,000	Indus International (b)(c)		16,016
		Enterprise Asset Management Software
	1,200,000	Parametric Technology (b)		15,252
		Engineering Software & Services
	2,075,000	Agile Software (b)		13,156
		Product Design Software
	1,240,000	webMethods (b)		12,239
		Enterprise Applications Integration (EAI) Tools
	1,100,000	Radiant Systems (b)		11,627
		Point of Sale System: Convenient Stores & Restaurants
	3,240,000	Tumbleweed Communications (b)(c)		9,234
		Email Content Security & File Transfer Management
	160,000	Kenexa (b)		5,096
		Human Capital Management Software
	241,000	MRO Software (b)		4,837
		Enterprise Maintenance Software
	1,250,000	ClickSoftware Technologies (b)		2,150
		Service Chain Optimization Software
				600,975
		>Business Information/ Business Services/Publishing: 1.5%
	2,585,000	Ceridian (b)		63,177
		HR Services & Payment Processing
	1,900,000	Navigant Consulting (b)		43,035
		Financial Consulting Firm
	600,000	Getty Images (b)		38,106
		Photographs for Publications & Electronic Media
	916,000	Fair Isaac		33,260
		Credit Scoring & Decision Analytic Software

Number of Shares			Value (000)
	2,000,000	Proquest Company (b)(c)	$	24,580
		Information Services for Educational & Automotive Services
	2,285,000	InfoUSA		23,558
		Business Data for Sales Leads
	1,500,000	Openwave Systems (b)		17,310
		Internet Software for Mobile Devices
	300,000	Navteq (b)		13,404
		Map Data for Electronic Devices
	2,500,000	PRIMEDIA (b)		4,575
		Specialty Magazines & Other Publications
	175,000	Triple Crown Media (b)		1,517
		Newspapers, Paging & Collegiate Sports Marketing
				262,522
		>Internet: 1.2%
	2,500,000	RSA Security (b)		67,975
		Enterprise Security Software
	9,500,000	Skillsoft Publishing (b)(c)		58,140
		Provider of Web-Based Learning Solutions (E-Learning)
	3,000,000	ValueClick (b)		46,050
		Internet Advertising
	4,000,000	CNET Networks (b)		31,920
		Internet Advertising on Niche Websites
	875,000	Vital Stream (b)		9,275
		Streaming Services for the Internet
	61,000	Travelzoo (b)		1,851
		Travel Internet Advertising
				215,211
		>Transaction Processors: 1.0%
	2,524,000	Global Payments		122,540
		Credit Card Processor
	6,500,000	Hong Kong Exchanges and Clearing (Hong Kong)		41,776
		Hong Kong Equity & Derivatives Market Operator
	600,000	Cubic		11,766
		Revenue Collection & Defense Systems
				176,082
		>Computer Services: 0.7%
	1,350,000	SRA International (b)		35,951
		Government I/T Services
	4,000,000	Bearing Point (b)		33,480
		Business Consulting & Technology Strategy
	5,000,000	Igate Capital (b)(c)		31,950
		I/T & BPO Outsourcing Services
	4,600,000	AnswerThink Consulting (b)(c)		18,538
		I/T Integration & Best Practice Research
				119,919
		>Electronics Distribution: 0.5%
	2,550,000	Avnet (b)		51,051
		Electronic Components Distribution
	680,000	Tech Data (b)		26,051
		I/T Distributor
	710,000	Agilysys		12,780
		I/T Distributor
				89,882

1-800-922-6769

Number of Shares			Value (000)
		>Consumer Software: 0.3%
	1,700,000	THQ (b)	$	36,720
		Entertainment Software
	1,000,000	Activision (b)		11,380
		Entertainment Software
				48,100
		Computer Related Hardware
		>Computer Hardware/ Related Systems: 3.3%
	1,620,000	Amphenol		90,655
		Electronic Connectors
	1,705,000	Belden CDT		56,350
		Specialty Cable
	870,000	Rogers (b)		49,016
		PCB Laminates & High Performance Foams
	4,425,000	Symbol Technologies		47,746
		Mobile Computers & Barcode Scanners
	1,634,000	Nice Systems (Israel) (b)		45,981
		Audio & Video Recording Solutions
	1,885,000	II VI (b)(c)		34,496
		Laser Components
	230,000	Wincor Nixdorf (Germany)		29,367
		Retail POS Systems & ATM Machines
	253,600	Neopost (France)		28,869
		Postage Meter Machines
	1,240,000	Intermec (b)		28,446
		Bar Code & Wireless LAN Systems
	9,761,000	Advantech (Taiwan)		28,019
		Embedded Computers
	1,027,000	Avocent (b)		26,959
		Computer Control Switches
	1,310,000	CTS		19,506
		Electronic Components, Sensors & EMS
	900,000	Netgear (b)		19,485
		Networking Products for Small Business & Home
	625,000	Excel Technologies (b)(c)		18,700
		Laser Systems & Electro-Optical Components
	530,000	Zebra Technologies (b)		18,105
		Bar Code Printers
	375,000	Diebold		15,233
		Automated Teller Machines
	1,875,000	Seachange International (b)(c)		13,050
		Systems for Video on Demand & Ad Insertion
	5,000,000	Concurrent Computer (b)(c)		13,050
		Video on Demand Systems & Services
	11,999,000	Phoenixtec Power (Taiwan)		12,196
		Uninterruptible Power Supplies
				595,229
		>Gaming Equipment: 1.4%
	2,750,000	International Game Technology		104,336
		Slot Machines & Progressive Jackpots
	2,430,000	Shuffle Master (b)(c)		79,655
		Card Shufflers & Casino Games
	3,900,000	Bally Technologies (b)(c)		64,233
		Slot Machines & Software
				248,224

Number of Shares			Value (000)
		>Semiconductors/ Related Equipment: 1.3%
	3,390,000	Integrated Device Technology (b)	$	48,070
		Communications Semiconductors
	4,425,000	Entegris (b)		42,170
		Semiconductor Wafer Shipping & Handling Products
	915,000	Littelfuse (b)		31,458
		Little Fuses
	690,000	Supertex (b)(c)		27,559
		Mixed-Signal Semiconductors
	1,950,000	AMIS Holdings (b)		19,500
		Analog & Mixed - Signal Semiconductors
	4,000,000	Novatek Microelectronics (Taiwan)		19,268
		LCD Related IC Designer
	1,905,000	IXYS (b)(c)		18,288
		Power Semiconductors
	1,235,000	Semtech (b)		17,846
		Analog Semiconductors
				224,159
		>Instrumentation: 1.2%
	1,250,000	Trimble Navigation (b)		55,800
		GPS-Based Instruments
	750,000	Mettler Toledo (b)		45,428
		Laboratory Equipment
	1,850,000	Flir Systems (b)		40,811
		Infrared Cameras
	711,000	Dionex (b)		38,863
		Ion & Liquid Chromatography
	670,000	Varian (b)		27,812
		Analytical Instruments
				208,714
		>Contract Manufacturing: 0.6%
	1,570,000	Plexus (b)		53,710
		Electronic Manufacturing Services
	1,705,000	Jabil Circuit		43,648
		Electronic Manufacturing Services
	4,000,000	Sanmina - SCI (b)		18,400
		BackPlane & Electronic Manufacturing Services
				115,758
		Telecommunications
		>Telecommunication Services: 3.1%
	4,500,000	Crown Castle International (b)		155,430
		Communication Towers
	3,500,000	American Tower (b)		108,920
		Communication Towers in USA & Mexico
	1,600,000	Alltel		102,129
		Cellular & Wireline Telephone Services
	4,250,000	Time Warner Telecom (b)(c)		63,113
		Fiber Optic Data/Telephone Service Provider
	8,000,000	Dobson Communications (b)(c)		61,840
		Rural & Small City Cellular Telephone Services
	780,000	Telephone and Data Systems		32,292
	300,000	Telephone and Data Systems, Cl. S		11,670
		Cellular & Wireline Telephone Services
	2,300,000	Tele2 AB (Sweden)		23,209
		European Mobile Operator & Services Reseller

Columbia Acorn Fund

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Telecommunication Services—continued
	200,000	Commonwealth Telephone	$	6,632
		Rural Phone Franchises & Competitive Telco
				565,235
		>Telecommunications Equipment: 0.9%
	10,000,000	Tellabs (b)		133,100
		Telecommunications Equipment
	1,380,000	Andrew (b)		12,227
		Wireless Infrastructure Equipment
	1,510,000	Symmetricom (b)		10,676
		Network Timing & Synchronization Devices
				156,003
		Media
		>Television Programming/CATV: 1.8%
	4,015,000	Discovery Holding (b)		58,739
		CATV Programming
	70,000	Jupiter Telecommunications (Japan) (b)		48,526
		Largest Cable Service Provider in Japan
	2,050,000	Liberty Global, Series C (b)		42,169
	1,750,000	Liberty Global, Series A (b)		37,625
		CATV Holding Company
	1,423,100	Alliance Atlantis Communication (Canada) (b)		41,687
		CATV Channels, TV/Movie Production/Distribution
	8,000,000	Gemstar-TV Guide International (b)		28,160
		TV Program Guides & CATV Programming
	3,000,000	Lions Gate Entertainment (b)		25,650
		Film & TV Studio
	655,000	Liberty Media - Interactive (b)		11,305
	130,000	Liberty Media - Capital (b)		10,890
		CATV Programming & Media Company Holdings
	1,250,000	Mediacom Communications (b)		7,787
		Cable Television Franchises
	700,000	Outdoor Channel (b)		7,224
		Cable Television Programming
				319,762
		>TV/Satellite Broadcasting: 0.4%
	2,752,829	SES Global (France)		39,212
		Satellite Broadcasting Services
	2,500,000	Entravision Communications (b)		21,425
		Spanish Language TV, Radio & Outdoor
	1,750,000	Gray Television		10,133
		Mid Market Affiliated TV Stations
	270,000	Metropole TV (France)		8,439
		Television Broadcaster
				79,209
		>Radio Broadcasting: 0.3%
	1,541,000	Salem Communications (b)(c)		20,048
		Radio Stations for Religious Programming
	1,500,000	Cumulus Media, Cl. A (b)		16,005
		Radio Stations in Small Cities
	1,400,000	Saga Communications (b)(c)		12,684
		Radio Stations in Small & Mid-sized Cities

Number of Shares			Value (000)
	2,400,000	Spanish Broadcasting System (b)(c)	$	12,264
		Spanish Language Radio Stations
				61,001
		Information: Total		4,085,985
Consumer Goods/Services: 18.5%
		Services
		>Retail: 5.3%
	5,960,000	Chico's FAS (b)		160,801
		Women's Specialty Retail
	2,200,000	Abercrombie & Fitch		121,946
		Teen Apparel Retailer
	2,760,000	Michaels Stores		113,822
		Craft & Hobby Specialty Retailer
	3,743,000	Christopher & Banks (c)		108,547
		Women's Apparel Retailer
	3,900,000	Urban Outfitters (b)		68,211
		Apparel & Home Specialty Retailer
	1,223,000	Ann Taylor Stores (b)		53,054
		Women's Apparel Retailer
	1,400,000	Williams Sonoma		47,670
		Home Goods & Furnishing Retailer
	2,250,000	Petco Animal Supplies (b)		45,968
		Pet Supplies & Services
	8,000,000	Rite Aid (b)		33,920
		Drug Stores
	1,100,000	J Crew Group (b)		30,195
		Multi-Channel Branded Retailer
	1,630,000	Rona (Canada) (b)		29,277
		Leading Canadian DIY Retailer
	936,000	Aeropostale (b)		27,041
		Mall Based Teen Retailer
	1,450,000	Borders Group		26,767
		Bookstores
	775,000	Genesco (b)		26,249
		Multi-Concept Branded Footwear Retailer
	750,000	Chattem (b)		22,778
		Personal Care Products
	1,062,000	Gaiam (b)(c)		14,889
		Healthy Living Catalogs & E-Commerce
	3,500,000	Edgars Consolidated Stores (South Africa)		14,109
		Leading Retail Conglomerate
				945,244
		>Consumer Services: 2.2%
	2,250,000	ITT Educational Services (b)(c)		148,073
		Post-secondary Degree Programs
	2,190,000	Pool Corporation		95,550
		Distributor of Swimming Pool Supplies and Equipment
	1,275,000	Weight Watchers		52,135
		Weight Loss Programs
	800,000	Regis Corp Minnesota		28,488
		Hair Salons
	1,530,000	Central Parking		24,480
		Owner, Operator & Manager of Parking Lots & Garages

1-800-922-6769

Number of Shares			Value (000)
		>Consumer Services—continued
	1,000,000	Universal Technical Institute (b)	$	22,020
		Vocational Training
	2,550,000	Princeton Review (b)(c)		13,566
		College Preparation Courses
	470,000	ServiceMaster		4,855
		Lawn Care, Pest Control, Commercial Disaster Response
	277,000	Lincoln Technical Institute (b)		4,734
		Vocational Training
	154,000	Park 24 (Japan)		4,523
		Parking Lot Operator
				398,424
		>Travel: 1.4%
	2,110,000	Vail Resorts (b)(c)		78,281
		Ski Resort Operator & Developer
	915,000	Four Seasons Hotels (Canada)		56,218
		Luxury Hotel Operator
	3,500,000	Expedia (b)		52,395
		Online Travel Service Company
	900,000	Intrawest (Canada)		28,444
		Ski Resort Operator & Developer
	270,000	Kerzner International (Bahamas) (b)		21,406
		Destination Resorts & Casinos
	1,045,000	Navigant International (b)(c)		16,751
		Corporate Travel Agency
	168,800	Localiza Rent A Car (Brazil)		3,234
		Car Rental
				256,729
		>Entertainment/Leisure Products: 1.1%
	1,795,000	RC2 (b)(c)		69,395
		Toys, Infant Products & Collectibles
	1,416,000	Speedway Motorsports		53,440
		Motorsport Racetrack Owner & Operator
	1,025,000	International Speedway Motors		47,529
		Largest Motorsport Racetrack Owner & Operator
	441,000	Thor Industries		21,366
		RV & Bus Manufacturer
	600,000	Callaway Golf		7,794
		Premium Golf Clubs & Balls
				199,524
		>Casinos & Gaming: 0.9%
	1,000,000	Station Casinos		68,080
		Casinos & Riverboats
	1,898,000	Pinnacle Entertainment (b)		58,174
		Regional Riverboat Casinos
	690,000	Intralot (Greece)		18,463
		Lottery & Gaming Systems & Services
	4,700,000	Sky City Entertainment (New Zealand)		15,448
		Casino/Entertainment Complex
	226,000	Lakes Entertainment (b)		2,732
		Native American Casino Development
				162,897
		>Restaurants: 0.7%
	2,145,000	Sonic (b)		44,595
		Quick Service Restaurant
	1,000,000	Red Robin Gourmet Burgers (b)(c)		42,560
		Casual Dining Restaurants

Number of Shares			Value (000)
	800,000	Cheesecake Factory (b)	$	21,560
		Casual Dining Restaurants
	1,600,000	AFC Enterprises (c)		20,400
		Popeye's Restaurants
				129,115
		>Cruise Lines: 0.1%
	400,000	Carnival		16,696
		Largest Cruise Line
		Goods
		>Apparel: 1.8%
	6,980,000	Coach (b)		208,702
		Designer & Retailer of Branded Leather Accessories
	1,418,000	Carter's (b)		37,478
		Children's Branded Apparel
	919,000	Oxford Industries (c)		36,218
		Branded & Private Label Apparel
	3,000,000	Billabong International (Australia)		34,250
		Action Sports Apparel Brand Manager
	700,000	True Religion Apparel (b)		12,390
		Premium Denim
				329,038
		>Furniture/Textiles: 1.7%
	2,550,000	HNI		115,643
		Office Furniture & Fireplaces
	765,000	Mohawk Industries (b)		53,818
		Carpet & Flooring
	2,068,000	Herman Miller		53,292
		Office Furniture
	1,398,000	Nobia (Sweden)		45,347
		Kitchen Cabinet Manufacturing & Distribution
	1,435,000	Knoll		26,347
		Office Furniture
				294,447
		>Leisure Vehicles: 1.2%
	1,751,000	Harley-Davidson		96,112
		Motorcycles & Related Merchandise
	1,130,000	Polaris Industries		48,929
		Leisure Vehicles & Related Products
	4,690,000	Fleetwood Enterprises (b)(c)		35,363
		RV & Manufactured Home Maker
	690,000	Winnebago		21,418
		Premier Motorhome Maker
	5,700,000	Ducati Motor (Italy) (b)		4,839
		Motorcycles & Related Merchandise
				206,661
		>Nondurables: 1.0%
	2,620,000	Scotts Miracle-Gro		110,878
		Consumer Lawn & Garden Products
	1,000,000	Jarden (b)		30,450
		Branded Household Products
	1,886,000	Prestige Brands (b)		18,803
		OTC, Household & Personal Care Products
	1,100,000	Natura Cosmeticos (Brazil)		11,529
		Direct Retailer of Cosmetics
				171,660

Columbia Acorn Fund

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Durable Goods: 0.6%
	465,000	Hyundai Mobis (South Korea)	$	39,290
		Auto Parts
	1,800,000	Helen of Troy (b)(c)		33,120
		Hairdryers & Curling Irons
	14,999,300	Techtronic Industries (Hong Kong)		20,273
		Power Tools & Motorized Appliances
	900,000	Champion Enterprises (b)		9,936
		Manufactured Homes
	172,000	Cavco Industries (b)		7,644
		Higher End Manufactured Homes
	90,000	Shimano (Japan)		2,758
		Bicycle Components & Fishing Tackle
				113,021
		>Food & Beverages: 0.5%
	1,597,000	IAWS Group (Ireland)		28,157
		Baked Goods
	2,410,000	Davide Campari (Italy)		24,965
		Spirits & Wine
	2,500,000	C&C Group (Ireland)		21,711
		Beverage Company
	35,000,000	Global Bio-Chem Technology Group (China)		14,800
		Refiner of Corn-Based Commodities
				89,633
		Consumer Goods/Services: Total		3,313,089
Industrial Goods/Services: 17.9%
		>Industrial Goods/Services: 3.3%
	1,900,000	Genlyte Group (b)(c)		137,617
		Commercial Lighting Fixtures
	3,600,000	Donaldson		121,932
		Industrial Air Filtration
	3,222,000	Clarcor (c)		95,983
		Mobile & Industrial Filters
	1,900,000	Mine Safety Appliances (c)		76,380
		Safety Equipment
	750,000	W.W. Grainger		56,422
		Industrial Distribution
	1,048,000	Drew Industries (b)		33,955
		RV & MFG Home Components
	1,600,000	Goodman Global (b)		24,288
		HVAC Equipment Manufacturer
	1,125,000	Ushio (Japan)		23,823
		Industrial Light Sources
	700,000	Legrand (France)		19,691
		Electrical Components
	141,000	Electric City (b)		155
		Electricity Conservation Devices
				590,246
		>Machinery: 3.2%
	2,200,000	Esco Technologies (b)(c)		117,590
		Automatic Electric Meter Readers
	2,350,000	Ametek		111,343
		Aerospace/Industrial Instruments
	2,750,000	Pentair		94,022
		Pumps, Water Treatment & Tools
	2,000,000	Gardner Denver (b)		77,000
		Air Compressors, Blowers & Pumps

Number of Shares			Value (000)
	1,500,000	Nordson	$	73,770
		Dispensing Systems for Adhesives & Coatings
	1,100,000	Kaydon		41,041
		Specialized Friction & Motion Control Products
	522,000	Toro		24,377
		Turf Maintenance Equipment
	1,187,000	K&F Industries Holdings (b)		21,046
		Aircraft Wheels, Brakes & Fuel Tank Bladders
	212,000	Oshkosh Truck		10,074
		Specialty Truck Manufacturer
				570,263
		>Logistics: 2.6%
	5,500,000	Expeditors International of Washington		308,055
		International Freight Forwarder
	2,000,000	Forward Air (c)		81,460
		Freight Transportation Between Airports
	3,000,000	UTI Worldwide		75,690
		Global Logistics & Freight Forwarding
				465,205
		>Industrial Distribution: 1.8%
	2,286,000	Watsco (c)		136,749
		HVAC Distribution
	1,925,000	Airgas		71,706
		Industrial Gas Distributor
	1,150,000	Aviall (b)		54,648
		Aircraft Replacement Parts Distributor
	3,500,000	Grafton Group (Ireland)		44,057
		Building Materials Wholesaling & DIY Retailing
	1,031,000	Nuco2 (b)(c)		24,785
		Bulk CO2 Gas Distribution to Restaurants
				331,945
		>Construction: 1.8%
	1,900,000	Florida Rock Industries		94,373
		Concrete & Aggregates
	2,200,000	Simpson Manufacturing		79,310
		Wall Joint Maker
	605,000	Martin Marietta		55,146
		Aggregates
	42,500	Geberit (Switzerland)		49,104
		Plumbing Supplies
	380,000	Daito Trust Construction (Japan)		21,128
		Apartment Builder
	1,000,000	Kingspan Group (Ireland)		17,459
		Building Insulation & Environmental Containers
	90,000	Ciments Francais (France)		14,962
		Leading French & Emerging Markets Cement Producer
				331,482
		>Steel: 1.3%
	2,860,000	Gibraltar Industries (c)		82,940
		Steel Processing
	1,500,000	Tenaris (Argentina)		60,735
		Oil, Gas & Industrial Seamless Tubes
	2,160,000	Worthington Industries		45,252
		Steel Processing

1-800-922-6769

Number of Shares			Value (000)
		>Steel—continued
	33,000	Vallourec (France)	$	39,673
		Oil, Gas & Industrial Seamless Tubes
				228,600
		>Specialty Chemicals & Industrial Materials: 1.2%
	2,800,000	Spartech (c)		63,280
		Plastics Distribution & Compounding
	730,000	Novozymes (Denmark)		49,201
		Industrial Enzymes
	28,000	Sika (Switzerland)		31,105
		Chemicals for Construction & Industrial Application
	400,000	Carbone Lorraine (France)		21,994
		Advanced Industrial Materials
	200,000	Imerys (France)		15,980
		Industrial Minerals Producer
	20,000	Givaudan (Switzerland)		15,728
		Fragrances & Flavors
	430,768	Koninklijke Ten Cate (Netherlands)		12,646
		Advanced Textiles & Industrial Fabrics
	438,000	Ultrapar (Brazil)		6,896
		Specialty Chemicals & Liquid Propane Gas Distribution
				216,830
		>Outsourcing Services & Training: 1.0%
	650,000	USG People (Netherlands)		49,754
		Temporary Staffing Services
	2,500,000	Quanta Services (b)		43,325
		Electrical & Telecom Construction Services
	1,100,000	Administaff		39,391
		Professional Employer Organization
	1,600,000	Labor Ready (b)		36,240
		Temporary Manual Labor
	600,000	GP Strategies (b)		4,626
		Training Programs
				173,336
		>Conglomerates: 0.6%
	765,342	Aalberts Industries (Netherlands)		56,261
		Flow Control & Heat Treatment
	1,325,058	Hexagon (Sweden)		48,238
		Measurement Equipment & Polymers
				104,499
		>Water: 0.6%
	2,500,000	Pall		70,000
		Filtration & Fluids Clarification
	900,000	Watts Water Technologies		30,195
		Water, Valves, Regulators & Filtration
				100,195
		>Other Industrial Services: 0.5%
	1,650,000	Mobile Mini (b)		48,279
		Portable Storage Unit Leasing
	374,000	IM Tech (Netherlands)		18,054
		Engineering & Technical Services
	655,000	Tal International (b)		15,786
		Intermodal Freight Container Leasing
	740,000	Jaakko Poyry (Finland)		7,956
		Engineering Consultants in Forestry, Energy
				90,075
		Industrial Goods/Services: Total		3,202,676

Number of Shares			Value (000)
Finance: 12.3%
		>Banks: 4.3%
	2,505,000	BOK Financial	$	124,423
		Tulsa Based S.W. Bank
	3,600,000	Associated Banc-Corp		113,508
		Midwest Bank
	3,156,000	TCF Financial		83,476
		Great Lakes Bank
	2,720,000	Glacier Bancorp (c)		79,614
		Mountain States Bank
	3,500,000	Anglo Irish Bank (Ireland)		54,536
		Small Business & Middle Market Banking
	2,850,000	Northern Rock (United Kingdom)		52,637
		Lowest Cost Mortgage Bank in UK
	1,320,000	West Coast Bancorp (c)		38,900
		Portland Small Business Lender
	2,275,000	Depfa Bank (Germany)		37,713
		Investment Banker to Public Authorities
	250,000	Komercni Banka (Czech Republic)		36,578
		Leading Czech Universal Bank
	590,000	CityBank Lynnwood (c)		27,529
		Seattle Real Estate Lender
	796,000	Great Southern Bancorp (c)		24,302
		Missouri Real Estate Lender
	892,000	Chittenden		23,058
		Vermont & Western Massachusetts Bank
	886,000	West Bancorporation (c)		16,542
		Des Moines Commercial Bank
	400,000	East West Bancorp		15,164
		LA Bank with Chinese Focus
	406,000	First Financial BankShares		14,835
		West Texas Bank
	500,000	Cascade Bancorp		14,255
		Central Oregon Bank
	304,000	S Y Bancorp		8,354
		Louisville Bank
	313,000	First Mutual Bancshares (c)		8,154
		Seattle Community Bank
	150,000	Greene County Bancshares		4,644
		Tennessee Bank
				778,222
		>Insurance: 3.1%
	2,040,000	Philadelphia Consolidated Holding (b)		61,934
		Specialty Insurance
	2,030,000	HCC Insurance Holdings		59,763
		Specialty Insurance
	1,200,000	Assurant		58,080
		Specialty Insurance
	1,748,000	Leucadia National		51,024
		Insurance Holding Company
	995,000	Protective Life		46,387
		Life Insurance
	710,000	Selective Insurance Group		39,668
		Commercial & Personal Lines Insurance
	109,000	Markel (b)		37,823
		Specialty Insurance
	1,550,000	United America Indemnity (b)(c)		32,302
		Specialty Insurance
	940,000	Endurance Specialty Holdings		30,080
		Commercial Lines Insurance/Reinsurance

Columbia Acorn Fund

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Insurance—continued
	1,700,000	Scottish Re Group	$	28,254
		Life Reinsurance
	570,000	RLI		27,463
		Specialty Insurance
	750,000	Delphi Financial Group		27,270
		Group Employee Benefit Products and Services
	600,000	National Financial		26,586
		Distributor of Life Insurance, Group Benefits & Inv adv svs
	520,000	StanCorp Financial		26,473
		Group Life & Disability Insurance
				553,107
		>Brokerage & Money Management: 1.8%
	2,464,000	SEI Investments		120,440
		Mutual Fund Administration & Investment Management
	3,970,000	Eaton Vance		99,091
		Specialty Mutual Funds
	1,757,000	Nuveen Investments		75,638
		Specialty Mutual Funds
	350,000	Investment Technology Group (b)		17,801
		Electronic Trading
				312,970
		>Finance Companies: 1.7%
	6,500,000	AmeriCredit (b)		181,480
		Auto Lending
	1,700,000	World Acceptance (b)(c)		60,384
		Personal Loans
	930,000	McGrath Rentcorp		25,863
		Temp Space & IT Equipment Rental
	1,120,000	Paragon Group (United Kingdom)		13,517
		UK Buy-to-Let Finance Company
	832,000	Electro Rent (b)		13,329
		Test & Measurement Rentals
	263,000	Marlin Business Services (b)		5,933
		National Small Equipment Leasing
	80,000	American Banknote (Brazil) (b)		517
		Manufacturer of Smart Cards
				301,023
		>Savings & Loans: 1.4%
	4,196,000	Peoples Bank Bridgeport		137,839
		Connecticut Savings & Loan
	1,700,000	Housing Development Finance (India)		41,847
		Premier Mortgage Lender in India
	1,178,000	Anchor Bancorp Wisconsin (c)		35,540
		Wisconsin Thrift
	1,285,000	Washington Federal		29,799
		Traditional Thrift
	360,000	Provident Bancorp		4,759
		New York State Thrift
				249,784
		Finance: Total		2,195,106
Energy/Minerals: 9.8%
		>Oil/Gas Producers: 5.0%
	3,200,000	Western Gas Resources		191,520
		Oil & Coal Seam Gas Producer

Number of Shares			Value (000)
	2,700,000	Ultra Petroleum (b)	$	160,029
		Natural Gas Producer
	2,500,000	XTO Energy		110,675
		Natural Gas Producer
	13,500,000	Tullow Oil (United Kingdom)		95,191
		Oil & Gas Producer
	4,900,000	Talisman Energy (Canada)		85,507
		Oil & Gas Producer
	2,400,000	Equitable Resources		80,400
		Natural Gas Producer & Utility
	2,000,000	Southwestern Energy (b)		62,320
		Natural Gas Producer
	1,500,000	Range Resources		40,785
		Oil & Gas Producer
	3,200,000	Vaalco Energy (b)(c)		31,232
		Oil & Gas Producer
	700,000	Denbury Resources (b)		22,169
		Oil Producer Using CO₂ Injection
	1,200,000	McMoran Exploration (b)		21,120
		Natural Gas Producer & Developer
	150,000	Hugoton Royalty		4,455
		Oil & Gas Producer
				905,403
		>Oil Services: 3.6%
	2,350,000	FMC Technologies (b)		158,531
		Oil & Gas Well Head Manufacturer
	2,728,301	Fugro (Netherlands)		117,626
		Survey & GPS Services
	2,300,000	Pride International (b)		71,829
		Offshore Drilling Contractor
	1,000,000	Atwood Oceanics Inc (b)		49,600
		Contract Drilling
	750,000	Carbo Ceramics		36,848
		Natural Gas Well Stimulants
	2,400,000	Key Energy Services (b)		36,600
		Well Workover Services
	971,000	Rowan		34,557
		Offshore Drilling Contractor
	1,193,000	Chicago Bridge & Iron		28,811
		Engineering & Construction for Petrochemicals & LNG
	1,140,000	Enerflex Systems (Canada) (c)		28,441
		Natural Gas Compresser Rental & Fabrication
	1,200,000	Saipem (Italy)		27,284
		Offshore Construction & Drilling
	350,000	Veritas DGC (b)		18,053
		Geophysical Contractor
	2,860,000	Newpark Resources (b)		17,589
		Drilling Fluid Services
	257,000	Helmerich & Payne		15,487
		Contract Driller
				641,256
		>Mining: 0.7%
	900,000	Falconbridge (Canada)		47,407
		Diversified Mining Holding Company
	13,100,000	UrAsia Energy (Canada)		32,859
		Uranium Mining in Kazakhstan
	195,000	Sociedad Quimica Y Minera de Chile (Chile)		20,307
		Producer of Specialty Fertilizers, Lithium & Iodine

1-800-922-6769

Number of Shares			Value (000)
		>Mining—continued
	2,900,000	Jubilee Gold Mines (Australia)	$	17,384
		Nickel Mining in Australia
	1,000,000	Ivanhoe Mines (Canada) (b)		6,772
		Copper Mining in Mongolia
				124,729
		>Distribution/Marketing/Refining: 0.3%
	966,000	Atmos Energy		26,961
		Dallas Natural Gas Utility
	600,000	Maritrans		14,940
		Shipping
	435,000	Oneok		14,807
		Natural Gas Distribution, Pipeline, Processing & Trading
				56,708
		>Agricultural Commodities: 0.2%
	550,000	Aracruz Celulose (Brazil)		28,831
		Brazilian Hardwood Pulp Producer
		Energy/Minerals: Total		1,756,927
Health Care: 7.8%
		>Medical Equipment/ Laboratory Supplies: 3.1%
	1,910,000	CYTYC (b)		48,438
		Consumables Related to Women's Health
	475,000	Essilor International (France)		47,764
		Eyeglass Lenses
	1,770,000	Intermagnetics General (b)		47,755
		MRI Equipment
	800,000	Diagnostic Products		46,536
		Immunodiagnostic Kits
	1,000,000	Edwards Lifesciences (b)		45,430
		Heart Valves
	870,000	Vital Signs (c)		43,091
		Anesthesia, Respiratory & Sleep Products
	1,000,000	ICU Medical (b)(c)		42,240
		Intravenous Therapy Products
	350,000	Synthes (Switzerland)		42,169
		Products for Orthopedic Surgery
	905,000	Arrow International		29,747
		Disposable Catheters
	552,000	Advanced Medical Optics (b)		27,986
		Medical Devices for Eye Care
	875,000	Viasys Healthcare (b)		22,400
		Respiratory & Neurology Medical Equipment
	583,000	Orthofix International (b)		22,230
		Bone Fixation & Stimulation Devices
	1,250,000	PSS World Medical (b)		22,063
		Medical Supplies Distributor
	390,000	Hogy Medical (Japan)		20,496
		Disposable Surgical Products
	415,000	Cooper		18,380
		Contact Lens Manufacturer
	350,000	Haemonetics (b)		16,279
		Blood & Plasma Collection Equipment
	455,000	Datascope		14,032
		Medical Devices
				557,036

Number of Shares			Value (000)
		>Services: 2.6%
	2,491,000	Lincare Holdings (b)	$	94,259
		Home Health Care Services
	1,232,000	Coventry Health Care (b)		67,686
		HMO
	1,607,000	Serologicals (b)		50,524
		Blood Collection & Antibody Production
	1,355,000	Charles River Laboratories (b)		49,864
		Pharmaceutical Research
	875,000	LCA Vision		46,296
		Lasik Surgery Centers
	1,000,000	Rhoen-Klinikum (Germany)		44,535
		Healthcare Services
	510,000	OPG Groep (Netherlands)		44,300
		Healthcare Supplies & Pharmacies
	900,000	United Surgical Partners (b)		27,063
		Outpatient Surgery Center
	808,000	PRA International (b)		17,994
		Contract Research Organization
	1,433,000	Dendrite International (b)		13,241
		Software for Pharmaceutical Sales Force Automation
	1,050,000	Eresearch Technology (b)		9,555
		Clinical Research Services
	500,000	Merge Technologies (b)		6,155
		Radiology Information Systems
				471,472
		>Biotechnology/Drug Delivery: 1.7%
	3,230,000	Exelixis (b)		32,461
		Treatments for Cancer & Metabolic Disorders
	1,360,000	Nektar Therapeutics (b)		24,942
		Drug Delivery Technologies
	2,380,000	Ligand Pharmaceuticals (b)		20,111
		Drugs for Pain, Cancer, Osteoporosis, & Diabetes
	2,000,000	Medarex (b)		19,220
		Humanized Antibodies
	1,650,000	Human Genome Sciences (b)		17,655
		Drug Discovery/Development
	1,100,000	Renovis (b)		16,841
		Drug to Minimize Neurological Damage from Strokes
	1,429,000	Arena Pharmaceuticals (b)		16,548
		Novel Drug Targeting Technology
	1,135,000	Keryx Biopharmaceuticals (b)		16,117
		Drugs for Diabetic Complications & Cancer
	2,520,000	Decode Genetics (b)		15,599
		Drugs for Heart Attack, Asthma & Vascular Disease
	1,780,000	Array Biopharma (b)		15,308
		Drugs for Cancer & Inflammatory Diseases
	930,000	Intermune (b)		15,299
		Drugs for Hepatitis C, Pulmonary Fibrosis & Cancer
	3,100,000	Lexicon Genetics (b)		13,609
		Drug Discovery
	2,000,000	Cytokinetics (b)(c)		12,580
		Drugs for Cancer & Heart Failure
	1,275,000	Rigel Pharmaceuticals (b)(c)		12,406
		Drugs for Hay Fever, Asthma, Hepatitis & Cancer

Columbia Acorn Fund

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Biotechnology/Drug Delivery—continued
	1,585,000	Maxygen (b)	$	11,856
		Molecular Breeding
	1,750,000	Genitope (b)		11,060
		Cancer Vaccine
	2,300,000	Seattle Genetics (b)		10,580
		Antibody-Based Therapies for Cancer
	800,000	Momenta Pharmaceuticals (b)		10,168
		Sugar Analysis Technology for Drug Design
	1,500,000	Tercica (b)		7,935
		Drug to Treat Severe Short Stature In Children
	1,100,000	La Jolla Pharmaceutical (b)		4,037
		Lupus Treatment
	1,249,999	Perlegen Sciences (d)		3,375
		Large Scale Gene Sequencing
	1,875,000	Locus Discovery, Series D, Pfd. (d)		512
		High Throughput Rational Drug Design
	359,944	Microdose (d)		360
		Drug Inhalers
				308,579
		>Medical Supplies: 0.4%
	486,000	Techne (b)		24,747
		Cytokines, Antibodies, Other Reagents For Life Sciences
	650,000	Owens & Minor		18,590
		Distribution of Medical Supplies
	4,000,000	United Drug (Ireland)		17,129
		Irish Pharmaceutical Wholesaler & Outsourcer
				60,466
		Health Care: Total		1,397,553
Other Industries: 4.7%
		>Real Estate: 3.6%
	5,850,000	Highland Hospitality (c)		82,368
		Hotel Owner
	650,000	SL Green Realty		71,155
		Manhattan Office Buildings
	1,398,000	Forest City Enterprises, Cl. B (c)		69,578
		Commercial & Residential Property Developer
	1,560,000	Gaylord Entertainment (b)		68,078
		Convention Hotels
	1,320,000	General Growth Properties		59,479
		Regional Shopping Malls
	3,294,000	DiamondRock Hospitality (c)		48,784
	1,000,000	DiamondRock Hospitality 144A (c)(d)		14,810
		Hotel Owner
	635,000	Macerich Company		44,577
		Regional Shopping Malls
	575,000	Federal Realty Investment Trust		40,250
		Shopping Centers
	1,020,000	Brandywine Realty		32,813
		Office Buildings
	1,720,000	Kite Realty Group (c)		26,815
		Community Shopping Centers
	1,375,000	Crescent Real Estate Equities		25,520
		Class A Office Buildings
	536,000	Parkway Properties		24,388
		Office Buildings

Number of Shares or Principal Amount			Value (000)
	900,000	American Campus Communities (c)	$	22,365
		Student Housing
	4,100	Kenedix (Japan)		17,754
		Real Estate Investment Management
	37,407	Security Capital European Realty (Luxembourg) (d)		531
		Self Storage Properties
				649,265
		>Transportation: 0.5%
	1,584,000	Heartland Express		28,338
		Regional Trucker
	1,086,000	JB Hunt		27,052
		Trucking Conglomerate
	760,000	Grupo Aeroportaurio Del Sureste (Mexico)		25,528
		Cancun & Cozumel Airport Operator
				80,918
		>Waste Management: 0.3%
	1,700,000	Waste Connections (b)		61,880
		Solid Waste Management
		>Regulated Utilities: 0.3%
	1,650,000	Northeast Utilities		34,106
		Regulated Electric Utility
	589,800	Red Electrica (Spain)		20,338
		Spanish Power Grid
				54,444
		Other Industries: Total		846,507
	Total Common Stocks and Other Equity-Like Securities: 93.8% (e) (Cost: $10,141,998)			16,797,843
Short-Term Obligations: 6.3%
$	176,000	Verizon Global Funding 5.18% - 5.35% Due 8/2/06 - 8/17/06		175,002
	161,000	HSBC Finance Corporation 5.04% - 5.05% Due 7/14/06 - 7/27/06		160,559
	155,000	American General Finance 5.01% - 5.06% Due 7/6/06 - 7/19/06		154,783
	154,000	Aluminum Company America 5.08% - 5.26% Due 7/3/06 - 8/9/06		153,478
	145,000	Credit Suisse First Boston 5.05% - 5.28% Due 7/13/06 - 8/11/06		144,325
	91,755	Hartford Financial 5.11% - 5.28% Due 7/28/06 - 8/10/06		91,319
	67,000	Conocophillips 5.09% Due 7/21/06 - 7/25/06		66,790
	60,000	Countrywide Financial Funding 5.30% - 5.40% Due 8/16/06		59,772
	40,000	Citigroup Funding 5.02% Due 08/01/06		39,823

1-800-922-6769

Principal Amount			Value (000)
		>Short-Term Obligations—continued
$	32,000	American Express Credit Corp 5.03% Due 7/10/06	$	31,960
	29,000	Bell South Corp 5.02% Due 7/12/06		28,983
	23,140	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/3/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 5/22/08 market value $23,605 (repurchase proceeds: $23,150)		23,140
		(Amortized Cost: $1,129,934)		1,129,934
	Total Investments: 100.1% (Cost: $11,271,932)(a)			17,927,777
	Cash and Other Assets Less Liabilities: (0.1%)			(11,701	)
	Total Net Assets: 100%		$	17,916,076

Columbia Acorn Fund

>Statement of Investments (Unaudited), continued

>Notes to Statement of Investments (in thousands)

(b) Non-income producing security.

AnswerThink Consulting	10.31	%
Christopher & Banks	10.25
Actuate	9.95
Highland Hospitality	9.79
Gibraltar Industries	9.60
Watsco	9.52
Indus International	9.49
Igate Capital	9.44
Princeton Review	9.24
World Acceptance	9.19
Skillsoft Publishing	8.79
Spartech	8.72
RC2	8.61
West Coast Bancorp	8.60
Kronos	8.58
Esco Technologies	8.53
Glacier Bancorp	8.41
Salem Communications	8.19
Saga Communications	7.69
Bally Technologies	7.48
Fleetwood Enterprises	7.35
ICU Medical	7.00
Concurrent Computer	6.92
Shuffle Master	6.92
Genlyte Group	6.75
Proquest Company	6.69
Nuco2	6.64
Vital Signs	6.61
Seachange International	6.55
Tumbleweed Communications	6.49
II VI	6.43
United America Indemnity	6.41
Forward Air	6.35	%
Navigant International	6.24
Clarcor	6.20
DiamondRock Hospitality	6.12
Red Robin Gourmet Burgers	6.04
Kite Realty Group	6.01
Helen of Troy	5.99
Spanish Broadcasting System	5.95
First Mutual Bancshares	5.88
Great Southern Bancorp	5.79
CityBank Lynnwood	5.67
IXYS	5.57
Time Warner Telecom	5.57
Vaalco Energy	5.55
Cytokinetics	5.48
Vail Resorts	5.41
Forest City Enterprises Class B	5.39
Anchor Bancorp Wisconsin	5.36
AFC Enterprises	5.35
Dobson Communications	5.31
West Bancorporation	5.30
American Campus Communities	5.23
Oxford Industries	5.21
Mine Safety Appliances	5.19
Excel Technologies	5.18
Gaiam	5.16
ITT Educational Services	5.14
Rigel Pharmaceuticals	5.13
JDA Software	5.10
Supertex	5.04
Enerflex Systems	5.02

Dividend income	$	13,299
Net realized gain or loss		—
Change in unrealized gain or loss		253,598
Purchases		262,161
Proceeds from sales		13,003

1-800-922-6769

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost (000)		Value (000)
DiamondRock Hospitality 144A	06/29/04		1,000,000	$	10,000	$	14,810
Perlegen Sciences	03/30/01		1,249,999		4,500		3,375
Security Capital European Realty (Luxembourg)	08/20/98 - 11/12/99		37,407		748		531
Locus Discovery, Series D Pfd.	09/05/01		1,875,000		7,500		512
Microdose	11/24/00		359,944		2,005		360
				$	24,753	$	19,588

(e) On June 30, 2006, the market value of foreign securities (in thousands) represents 13.70% of total net assets. The Fund's foreign portfolio was diversified as follows:

	Value		Percent
Canada	$	356,612		1.99	%
Netherlands		298,641		1.67
France		236,584		1.32
Ireland		183,049		1.02
United Kingdom		161,345		0.90
Japan		139,008		0.78
Switzerland		138,106		0.77
Sweden		116,794		0.65
Germany		111,615		0.62
Hong Kong		62,049		0.35
Luxembourg		61,266		0.34
Taiwan		59,483		0.33
Italy		57,088		0.32
Australia		51,635		0.29
Brazil		51,007		0.29
	Value		Percent
Denmark	$	49,201		0.28	%
Israel		45,981		0.26
India		41,847		0.23
South Korea		39,290		0.22
Czech Republic		36,578		0.20
Mexico		25,528		0.14
Bahamas		21,406		0.12
Spain		20,338		0.11
Chile		20,307		0.11
Greece		18,463		0.10
New Zealand		15,448		0.09
China		14,800		0.08
South Africa		14,109		0.08
Finland		7,956		0.04
Total Foreign Portfolio	$	2,455,534		13.70	%

Columbia Acorn International

>Major Portfolio Changes in the Second Quarter (Unaudited)

	Number of Shares
	03/31/06		06/30/06
Additions
Europe
>France
Carbone Lorraine		340,000		395,000
Eurofins Scientific		320,000		360,000
Foncia Groupe		0		400,000
Legrand		0		700,000
Neopost		236,000		280,000
Norbert Dentressangle		300,000		375,000
Trigano		423,000		500,000
>United Kingdom
Randgold Resources		0		640,000
UTV		1,800,000		2,000,000
>Netherlands
Aalberts Industries		550,000		557,534
Fugro		1,245,000		1,268,491
IM Tech		474,000		574,000
>Germany
Depfa Bank		1,675,000		2,000,000
Rational AG		0		75,000
>Switzerland
Givaudan		15,000		25,000
Kuehne & Nagel		95,000		475,000
Synthes		215,000		275,000
>Italy
Amplifon		1,700,000		2,000,000
(includes the effect of a 10 for 1 stock split)
Cir Compagnie		6,000,000		9,100,000
Ducati Motor		6,400,000		12,800,000
GranitiFiandre		275,000		1,223,000
>Sweden
Sweco		380,000		422,000
Tele2		2,100,000		2,580,000
>Poland
Central European Distribution		448,000		820,500
(includes the effect of a 3 for 2 stock split)

	Number of Shares
	03/31/06		06/30/06
Asia
>Japan
FCC		454,000		714,000
Kansai Paint		882,000		3,700,000
Sparx Asset Management		0		22,500
Other Countries
>Canada
Alliance Atlantis Communication		639,000		1,060,000
UrAsia Energy		0		1,475,000
Van Houtte		0		950,000
>Australia
Sino Gold		0		5,450,000
>South Africa
Impala Platinum		140,000		180,000
>United States
Atwood Oceanics		0		415,000
>New Zealand
Sky City Entertainment		5,000,000		5,500,000
Latin America
>Brazil
American Banknote		0		1,085,000
Localiza Rent a Car		0		170,000
Suzano		3,215,000		4,300,000

1-800-922-6769

	Number of Shares
	03/31/06		06/30/06
Sales
Europe
>France
Essilor International		300,000		200,000
Vallourec		20,000		0
>United Kingdom
Bloomsbury Publishing		2,000,000		916,000
Intermediate Capital		600,000		0
Kensington Group		1,050,000		813,050
>Germany
Bilfinger Berger		300,000		200,000
>Ireland
Anglo Irish Bank		2,260,000		2,200,000
>Switzerland
BKW Energie		130,000		27,000
>Sweden
Gambro		2,042,000		0
>Spain
Abengoa		370,000		0
>Russia
RBC Information Systems		700,000		575,800

	Number of Shares
	03/31/06		06/30/06
Asia
>Japan
Meitec		475,000		0
Shimano		900,000		650,000
>Taiwan
Novatek Microelectronics		3,244,000		3,000,000
>Hong Kong
Hong Kong Exchanges and Clearing		6,000,000		5,000,000
Linmark Group		13,483,000		10,996,000
>South Korea
Samsung Fire & Marine		100,000		0
>Indonesia
Perusahaan Gas Negara		20,000,000		15,000,000
>Singapore
Comfort Del Gro		20,000,000		7,053,000
Other Countries
>Canada
Kinross Gold		1,100,000		835,000
>Australia
ABC Learning Center		4,028,250		4,000,000
Latin America
>Brazil
America Latina Logistics		280,000		0
Diagnosticos		590,000		392,000
Natura Cosmeticos		3,200,000		2,500,000
Porto Seguro		1,000,000		720,000
Ultrapar		500,000		293,000

Columbia Acorn International

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares			Value (000)
			Common Stocks: 95.9%
Europe: 59.2%
		>France: 11.5%
	700,000	April Group	$	37,576
		Insurance Policy Construction
	390,000	Iliad		32,484
		High Speed Internet Service Provider
	280,000	Neopost		31,875
		Postage Meter Machines
	2,200,000	SES Global		31,338
		Satellite Broadcasting Service
	411,000	Rubis		28,755
		Tank Storage & LPG Supplier
	500,000	Trigano		26,540
		Leisure Vehicles & Camping Equipment
	375,000	Norbert Dentressangle		26,380
		Transport
	360,000	Eurofins Scientific (b)		23,436
		Food Screening & Testing
	206,000	Pierre & Vacances		22,580
		Vacation Apartment Lets
	395,000	Carbone Lorraine		21,719
		Advanced Industrial Materials
	200,000	Essilor International		20,111
		Eyeglass Lenses
	120,000	Ciments Francais		19,949
		Leading French & Emerging Markets Cement Producer
	700,000	Legrand		19,691
		Electrical Components
	240,000	Imerys		19,176
		Industrial Minerals Producer
	151,000	Bacou Dalloz		17,981
		Safety Equipment
	400,000	Foncia Groupe		17,646
		Real Estate Services
	550,000	Metropole Television		17,190
		Television Broadcaster
				414,427
		>United Kingdom: 8.6%
	6,370,000	Tullow Oil		44,915
		Oil & Gas Producer
	1,850,000	Northern Rock		34,168
		Lowest Cost Mortgage Bank in UK
	2,800,000	Paragon Group		33,792
		Buy-To-Let Finance Company
	7,200,000	RPS Group		28,825
		Environmental Consulting & Planning
	1,850,000	Expro International Group		23,212
		Offshore Oilfield Services
	1,200,000	Northgate		23,211
		Light Commercial Vehicle Rental Specialist
	4,200,000	Taylor Nelson Sofres		18,065
		Market Research
	3,550,000	BBA Group		17,346
		Aviation Support Services & Non-Woven Materials
	2,450,000	Workspace Group		16,380
		Real Estate
	813,050	Kensington Group		15,460
		Non-Conforming Mortgage Company

Number of Shares			Value (000)
	1,300,000	Keller Group	$	13,967
		International Ground Engineering Specialist
	640,000	Randgold Resources (b)		13,440
		Gold Mining in Western Africa
	2,000,000	UTV		12,575
		Irish Television & Radio Station Operator
	450,000	Viridian Group		7,952
		Northern Ireland Electric Utility
	916,000	Bloomsbury Publishing		5,485
		Book Publisher
				308,793
		>Netherlands: 8.3%
	1,268,491	Fugro		54,689
		Survey & GPS Services
	679,000	USG People		51,973
		Temporary Staffing Services
	557,534	Aalberts Industries		40,985
		Flow Control & Heat Treatment
	972,304	Koninklijke Ten Cate		28,545
		Advanced Textiles & Industrial Fabrics
	327,000	OPG Groep		28,405
		Healthcare Supplies & Pharmacies
	574,000	IM Tech		27,709
		Engineering & Technical Services
	439,400	Sligro Food Group		23,327
		Food Service & Wholesaling
	330,000	Smit Internationale		23,216
		Harbor & Offshore Towage & Marine Services
	890,000	Unit 4 Agresso (b)		17,901
		Business & Security Software
				296,750
		>Germany: 7.9%
	900,000	Rhoen-Klinikum		40,082
		Health Care Services
	275,000	Wincor Nixdorf		35,112
		Retail POS Systems & ATM Machines
	2,000,000	Depfa Bank		33,154
		Investment Banker to Public Authorities
	27,500	Porsche		26,536
		Specialty Automobile Manufacturer
	775,000	CTS Eventim (b)		23,763
		Event Ticket Sales
	450,000	Hugo Boss Designs		18,943
		Fashion Apparel
	260,000	Grenkeleasing		17,292
		Financing for IT Equipment
	320,000	Vossloh		16,225
		Rail Infrastructure & Diesel Locomotives
	415,000	GFK		15,128
		Market Research Services
	870,000	Takkt		13,828
		Mail Order Retailer of Office & Warehouse Durables
	100,000	Deutsche Boerse		13,597
		Trading, Clearing, Settlement Services for Financial Markets
	75,000	Rational		12,248
		Commercial Oven Manufacturer
	200,000	Bilfinger Berger		10,856
		Construction & Related Services

1-800-922-6769

Number of Shares			Value (000)
		>Germany—continued
	296,000	Deutsche Beteiligungs	$	6,172
		Private Equity Investment Management
				282,936
		>Ireland: 6.1%
	2,000,000	Bank of Ireland		35,801
		Irish Commercial Bank
	2,000,000	IAWS Group		35,262
		Baked Goods
	2,200,000	Anglo Irish Bank		34,280
		Small Business & Middle Market Banking
	2,350,000	Grafton Group		29,581
		Builders Materials Wholesaling & Do-it-yourself Retailing
	6,856,625	United Drug		29,361
		Irish Pharmaceutical Wholesaler & Outsourcer
	2,500,000	C&C Group		21,712
		Beverage Company
	1,150,000	Kingspan Group		20,078
		Building Insulation & Environmental Containers
	720,000	Paddy Power		12,470
		Irish Betting Services
				218,545
		>Switzerland: 4.9%
	30,000	Geberit		34,662
		Plumbing Supplies
	475,000	Kuehne & Nagel		34,579
		Freight Forwarding/Logistics
	275,000	Synthes		33,132
		Products for Orthopedic Surgery
	24,000	Sika		26,661
		Chemicals for Construction & Industrial Applications
	25,000	Givaudan		19,660
		Fragrances & Flavors
	300,000	Schindler		15,535
		Elevator Manufacturer & Service Provider
	275,000	Logitech (b)		10,602
		Branded Peripheral Computer Devices
	27,000	BKW Energie		2,364
		Electric Utility
				177,195
		>Italy: 3.3%
	9,100,000	Cir Compagnie		25,899
		Italian Holding Company
	2,120,000	Davide Campari		21,961
		Spirits & Wines
	404,000	Banca Italease		20,188
		Italian Leasing & Factoring Leader
	2,000,000	Amplifon		16,999
		Hearing Aid Retailer
	1,223,000	GranitiFiandre		13,163
		Innovative Stoneware
	12,800,000	Ducati Motor (b)		10,867
		Motorcycles & Related Merchandise
	350,000	Sabaf		9,961
		Supplier to White Goods OEMS
				119,038

Number of Shares			Value (000)
		>Sweden: 3.3%
	1,544,998	Hexagon	$	56,245
		Measurement Equipment & Polymers
	2,580,000	Tele2		26,034
		European Mobile Operator & Services Reseller
	755,000	Nobia		24,490
		Kitchen Cabinet Manufacturing & Distribution
	422,000	Sweco		11,541
		Engineering Consultants
				118,310
		>Russia: 1.1%
	775,000	Novolipetsk Steel		16,999
		Vertically Integrated Steel Producer
	575,800	RBC Information Systems (b)		15,202
		Financial Information, Media & IT Services in Russia
	370,000	Mechel Steel Group		8,284
		Coking Coal
				40,485
		>Spain: 0.8%
	620,000	Red Electrica		21,379
		Spanish Power Grid
	120,700	Bankinter		7,768
		Mortgage Lender
				29,147
		>Czech Republic: 0.7%
	183,000	Komercni Banka		26,775
		Leading Czech Universal Bank
		>Greece: 0.7%
	936,000	Intralot		25,045
		Lottery & Gaming Systems/Services
		>Poland: 0.6%
	820,500	Central European Distribution (b)		20,644
		Vodka Production & Alcohol Distribution
		>Finland: 0.5%
	1,756,000	Jaakko Poyry		18,880
		Engineering Consultants
		>Denmark: 0.5%
	280,000	Novozymes		18,872
		Industrial Enzymes
		>Austria: 0.4%
	300,000	Wienerberger		14,255
		Bricks & Clay Roofing Tiles
		Europe: Total		2,130,097
Asia: 21.5%
		>Japan: 15.2%
	546,000	Daito Trust Construction		30,358
		Apartment Builder
	43,500	Jupiter Telecommunications (b)		30,155
		Largest Cable Service Provider in Japan

Columbia Acorn International

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Japan—continued
	3,700,000	Kansai Paint	$	29,606
		Paint Producer in Japan, India, China & Southeast Asia
	1,272,000	Ushio		26,935
		Industrial Light Sources
	718,000	Ito En		26,340
		Bottled Tea & Other Beverages
	868,000	Park 24		25,496
		Parking Lot Operator
	600,000	Aeon Mall		25,180
		Suburban Shopping Mall Developer, Owner & Operator
	453,000	Hogy Medical		23,806
		Disposable Surgical Products
	22,500	Sparx Asset Management		23,516
		Fund Management
	350,000	USS		23,172
		Used Car Auctioneer
	600,000	Hoya		21,450
		Opto-Electrical Components & Eyeglass Lenses
	785,000	JSR		19,922
		Films & Chemicals for LCD Screens & Electronics
	650,000	Shimano		19,922
		Bicycle Components & Fishing Tackle
	2,000,000	Chiba Bank		18,773
		Regional Bank
	4,310	Kenedix		18,665
		Real Estate Investment Management
	220,000	Fast Retailing		17,914
		Apparel Retailer
	710,000	Sato		16,445
		Bar Code Printers & Supplies
	714,000	FCC		14,176
		Auto/Motorcycle Clutches
	965,000	T. Hasegawa		13,774
		Industrial Flavors & Fragrances
	2,248,000	Hiroshima Bank		13,740
		Regional Bank
	918,000	Toyo Technica		12,665
		Value Added Reseller of Imported Instrumentation
	2,960	Risa Partners		11,762
		NPL & Real Estate Related Investment
	1,500,000	Bank of Fukuoka		11,465
		Regional Bank
	960	Osaka Securities Exchange		11,407
		Osaka Securities Exchange
	1,650	Japan Pure Chemical		10,713
		Precious Metal Plating Chemicals for Electronics
	430,000	Yusen Air & Sea Service		10,105
		Airfreight Logistics
	1,230,000	Kamigumi		9,349
		Port Cargo Handling & Logistics
	375,000	Nagaileben		8,438
		Medical/Healthcare Related Clothes
	321,100	Kintetsu World Express		7,623
		Airfreight Logistics
	450,200	Ain Pharmaciez		7,483
		Dispensing Pharmacy/Drugstore Operator
	1,713	Advance Create		4,973
		Independent Insurance Distributor
				545,328

Number of Shares			Value (000)
		>Taiwan: 2.1%
	6,822,000	Advantech	$	19,583
		Embedded Computers
	18,300,000	Phoenixtec Power		18,601
		Uninterruptible Power Supplies
	3,000,000	Novatek Microelectronics		14,451
		LCD Related IC Designer
	7,280,000	Wah Lee Industrial		13,352
		Distributor of Chemicals, Materials, & Equipment
	7,186,000	Springsoft		11,084
		Electronic Design Automation Software
				77,071
		>Hong Kong: 1.5%
	5,000,000	Hong Kong Exchanges and Clearing		32,136
		Hong Kong Equity & Derivatives Market Operator
	14,000,000	Techtronic Industries		18,922
		Power Tools & Motorized Appliances
	10,996,000	Linmark Group		1,731
		Global Sourcing Agent of Consumer Goods
				52,789
		>India: 0.9%
	1,300,000	Housing Development Finance		32,001
		Indian Mortgage Lender
		>South Korea: 0.6%
	250,000	Hyundai Mobis		21,124
		Auto Parts
		>China: 0.5%
	45,000,000	Global Bio-Chem Technology Group		19,028
		Refiner of Corn-based Commodities
		>Indonesia: 0.5%
	15,000,000	Perusahaan Gas Negara		18,192
		Gas Pipeline Operator
		>Singapore: 0.2%
	7,053,000	Comfort Del Gro		6,798
		Taxi & Mass Transit Service
		Asia: Total		772,331
Other Countries: 10.7%
		>Canada: 5.3%
	1,060,000	Alliance Atlantis Communication (b)		31,051
		CATV Channels, TV/Movie Production/Distribution
	1,370,000	Rona (b)		24,607
		Leading Canadian Do-it-yourself Retailer
	400,000	Falconbridge		21,070
		Diversified Mining Holding Company
	1,155,000	Talisman Energy		20,155
		Oil & Gas Producer
	1,190,000	Shawcor		17,685
		Oilfield Services
	6,775,000	UrAsia Energy (b)		16,994
		Uranium Mining in Kazakhstan

1-800-922-6769

Number of Shares			Value (000)
		>Canada—continued
	950,000	Van Houtte (c)	$	15,795
		Coffee Services & Equipment
	530,000	Major Drilling Group (b)		10,597
		Mining Exploration Driller
	2,000,000	Northern Orion Resources (b)		9,818
		Copper & Gold Mining in Argentina
	835,000	Kinross Gold (b)		9,103
		Gold Mining
	850,000	Ivanhoe Mines (b)		5,757
		Copper Mine Project in Mongolia
	2,036,000	RailPower Technologies 144A (b)(c)(d)		4,377
	789,000	RailPower Technologies (c)		1,696
		Hybrid Locomotives
				188,705
		>Australia: 2.9%
	3,000,000	Billabong International		34,250
		Action Sports Apparel Brand Manager
	5,450,000	Sino Gold (b)		20,343
		Gold Mining in The People's Republic of China
	4,000,000	ABC Learning Center		19,036
		Childcare Centers
	350,000	Perpetual Trustees		19,034
		Mutual Fund Management
	2,000,000	Jubilee Mines		11,989
		Nickel Mining in Australia
				104,652
		>South Africa: 1.4%
	180,000	Impala Platinum		33,085
		Platinum Group Metals Mining & Refining
	4,500,000	Edgars Consolidated Stores		18,140
		Leading Retail Conglomerate
				51,225
		>United States: 0.6%
	415,000	Atwood Oceanics (b)		20,584
		Contract Drilling
		>New Zealand: 0.5%
	5,500,000	Sky City Entertainment		18,078
		Casino/Entertainment Complex
		Other Countries: Total		383,244
Latin America: 4.5%
		>Brazil: 2.4%
	2,500,000	Natura Cosmeticos		26,202
		Direct Retailer of Cosmetics
	4,300,000	Suzano		25,273
		Pulp & Paper Producer
	720,000	Porto Seguro (b)		12,300
		Auto & Life Insurance
	392,000	Diagnosticos (b)		7,782
		Medical Diagnostic Services

Number of Shares or Principal Amount			Value (000)
	1,085,000	American Banknote (b)	$	7,013
		Manufacturer of Smart Cards
	293,000	Ultrapar		4,613
		Specialty Chemicals & Liquid Propane Gas Distribution
	170,000	Localiza Rent A Car		3,257
		Car Rental
				86,440
		>Mexico: 1.3%
	4,500,000	Consorcio ARA		18,530
		Affordable Housing Builder
	414,000	Grupo Aeroportuario Del Sureste		13,906
		Cancun/Cozumel Airport Operator
	4,200,000	Urbi Desarrollo (b)		9,740
		Affordable Housing Builder
	100,000	Grupo Aeroportuario Del Pacifia		3,185
		Mexican Airport Operator
				45,361
		>Chile: 0.4%
	160,000	Sociedad Quimica y Minera de Chile (Chile)		16,662
		Producer of Specialty Fertilizers, Lithium, & Iodine
		>Argentina: 0.4%
	350,000	Tenaris		14,172
		Oil, Gas & Industrial Seamless Tubes
		Latin America: Total		162,635
	Total Common Stocks: 95.9% (Cost: $2,361,806)			3,448,307
Short-Term Obligations: 3.4%
$	75,000	Conocophillips 5.30% Due 7/03/06 - 7/05/06		74,966
	45,000	Countrywide Financial Funding 5.30% Due 7/06/06		44,967
	4,181	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/3/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 5/9/09 market value $4,268 (repurchase proceeds: $4,183)		4,181
		(Amortized Cost: $124,114)		124,114
	Total Investments: 99.3% (Cost: $2,485,920)(a)(e)			3,572,421
	Cash and Other Assets Less Liabilities: 0.7%			23,881
	Total Net Assets: 100%		$	3,596,302

Columbia Acorn International

>Statement of Investments (Unaudited), continued

>Notes to Statement of Investments (in thousands)

(b) Non-income producing security.

Van Houtte					5.91	%
RailPower Technologies					5.16	%

Dividend Income	$	58
Net realized gain or loss		—
Change in unrealized gain or loss		(10,121	)
Purchases		18,278
Proceeds from sales		2

Additional information on this security is as follows:

Security				Acquisition Dates				Shares				Cost (000)				Value (000)
RailPower Technologies 144A					11/10/05 - 11/18/05				2,036,000			$	9,220			$	4,377

(e) On June 30, 2006, the Fund's total investments were denominated in currencies as follows:

Currency	Value		% of Total Net Assets
Euro	$	1,419,023		39.5	%
Japanese Yen		545,329		15.2
British Pounds		295,353		8.2
Canadian Dollar		188,705		5.2
Other currencies less than 5% of total net assets		1,124,011		31.2
	$	3,572,421		99.3	%

1-800-922-6769

Columbia Acorn International

>Portfolio Diversification

At June 30, 2006, the Fund's portfolio investments as a percent of net assets was diversified as follows:

	Value (000)		Percent
>Industrial Goods/Services
Other Industrial Services	$	167,388		4.6	%
Specialty Chemicals		160,483		4.5
Construction		144,124		4.0
Industrial Materials		117,554		3.3
Conglomerates		97,230		2.7
Machinery		82,867		2.3
Outsourcing & Training Services		69,320		1.9
Electrical Components		46,626		1.3
Steel		31,171		0.9
Industrial Distribution		29,581		0.8
		946,344		26.3
>Consumer Goods/Services
Retail		110,323		3.1
Durables Goods		100,385		2.8
Beverage		85,808		2.4
Other Consumer Services		84,757		2.4
Food		58,589		1.6
Apparels		54,924		1.5
Consumer Goods Distribution		43,816		1.2
Gaming		37,516		1.0
Leisure Products		26,540		0.7
Nondurables		26,202		0.7
Furniture & Textiles		24,490		0.7
Entertainment		23,763		0.7
Casinos		18,078		0.5
Travel		3,257		0.1
		698,448		19.4
>Information
Computer Hardware & Related Equipment		83,898		2.3
Business Information & Marketing Services		62,018		1.7
Financial Processors		45,732		1.3
Semiconductors & Related Equipment		35,900		1.0
Internet Related		32,484		0.9
Satellite Broadcasting		31,338		0.9
Television Programming		31,051		0.9
Cable Television		30,155		0.8
Television Broadcasting		29,764		0.8
Business Software		28,986		0.8
Telephone Services		26,034		0.7
Computer Services		15,201		0.4
Electronics Distribution		13,352		0.4
Instrumentation		12,665		0.4
Publishing		5,485		0.2
		484,063		13.5

	Value (000)		Percent
>Finance
Banks	$	208,157		5.8	%
Other Finance Companies		121,350		3.4
Insurance		54,849		1.5
Money Management		48,722		1.4
Savings & Loans		39,769		1.1
Credit Cards		7,013		0.2
		479,860		13.4
>Energy/Minerals
Mining		149,883		4.2
Oil Services		116,170		3.2
Oil/Gas Producers		65,071		1.8
Refining/Marketing/ Distribution		46,948		1.3
Agricultural Commodities		44,301		1.2
Non-Ferrous Metals		10,597		0.3
		432,970		12.0
>Other Industries
Transportation		82,834		2.3
Real Estate		75,076		2.1
Regulated Utilities		57,594		1.6
		215,504		6.0
>Health Care
Services		68,486		1.9
Medical Equipment		53,244		1.5
Hospital/Laboratory Supplies		40,027		1.1
Pharmaceuticals		29,361		0.8
		191,118		5.3
Total Common Stocks		3,448,307		95.9
Short-Term Obligations		124,114		3.4
Total Investments		3,572,421		99.3
Cash and Other Assets Less Liabilities		23,881		0.7
Total Net Assets	$	3,596,302		100.0	%

Columbia Acorn USA

>Major Portfolio Changes in the Second Quarter (Unaudited)

	Number of Shares
	03/31/06		06/30/06
Additions
Information
Avid Technology		454,900		779,900
Concur Technologies		30,400		230,400
Gemstar-TV Guide International		2,375,653		2,580,000
II VI		435,000		505,000
Kronos		500,650		660,650
Nice Systems (Israel)		456,600		566,600
(includes the effect of a 2 for 1 stock split)
Openwave Systems		0		100,000
Progress Software		118,600		347,000
Saga Communications		98,100		300,000
Time Warner Telecom		786,000		1,086,000
Trimble Navigation		90,000		125,000
ValueClick		285,000		460,000
webMethods		83,500		279,100
Consumer Goods/Services
Carter's		80,200		545,200
(includes the effect of a 2 for 1 stock split)
J Crew Group		0		125,000
Oxford Industries		529,200		634,200
Petco Animal Supplies		428,000		608,000
Red Robin Gourmet Burgers		68,800		163,800
True Religion Apparel		205,000		675,200
Health Care
LCA-Vision		143,995		210,000
PSS World Medical		150,000		380,000
United Surgical Partners		150,000		550,000
Industrial Goods/Services
Goodman Global		0		132,000
Simpson Manufacturing		0		100,000
Other Industries
Highland Hospitality		235,000		350,000
Energy/Minerals
Atwood Oceanics		0		152,000
Finance
Delphi Financial Group		29,000		87,000
(includes the effect of a 3 for 2 stock split)

	Number of Shares
	03/31/06		06/30/06
Sales
Information
CDW		28,000		0
Getty Images		104,800		44,000
Global Payments		423,280		393,280
JDA Software		723,800		524,000
MRO Software		242,000		57,950
Plexus		131,100		105,000
Tellabs		1,610,000		1,525,000
Consumer Goods/Services
Aeropostale		200,000		130,000
Sports Authority		105,000		0
Health Care
Charles River Laboratories		303,000		258,000
Incyte		450,000		0
Neurocrine Biosciences		192,000		0
Energy/Minerals
Chicago Bridge & Iron		585,000		535,000
Newpark Resources		1,001,000		350,900
Pioneer Drilling		266,800		0

1-800-922-6769

Columbia Acorn USA

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares			Value (000)
			Common Stocks: 91.5%
Information: 31.2%
		>Business Software: 8.2%
	779,900	Avid Technology (b)	$	25,994
		Digital Nonlinear Editing Software & Systems
	660,650	Kronos (b)		23,922
		Labor Management Solutions
	455,200	Micros Systems (b)		19,883
		Information Systems for Restaurants & Hotels
	2,100,000	Novell (b)		13,923
		Directory, Operating System & Identity Management Software
	347,000	Progress Software (b)		8,123
		Application Development Software
	405,800	SSA Global Technologies (b)		7,864
		Enterprise Resource Planning Software
	524,000	JDA Software (b)		7,352
		Application/Software & Services for Retailers
	327,200	Parametric Technology (b)		4,159
		Engineering Software & Services
	230,400	Concur Technologies (b)		3,564
		Web Enabled Cost & Expense Management Software
	279,100	webMethods (b)		2,755
		Enterprise Applications Integration Tools
	59,300	Witness Systems (b)		1,196
		Customer Experience Management Software
	57,950	MRO Software (b)		1,163
		Enterprise Maintenance Software
				119,898
		>Mobile Communications: 5.9%
	1,005,000	Crown Castle International (b)		34,713
		Communications Towers
	356,605	Alltel		22,762
		Cellular & Wireline Telephone Services
	506,000	American Tower (b)		15,747
		Communications Towers in USA & Mexico
	1,633,000	Dobson Communications (b)		12,623
		Rural & Small City Cellular Telephone Services
	100,000	Openwave Systems (b)		1,154
		Internet Software for Mobile Devices
				86,999
		>Computer Hardware and Related Equipment: 4.1%
	566,600	Nice Systems (Israel) (b)		15,944
		Audio & Video Recording Solutions
	505,000	II VI (b)		9,242
		Laser Components
	147,800	Amphenol		8,271
		Electronic Connectors
	584,000	Symbol Technologies		6,301
		Mobile Computers & Barcode Scanners
	260,000	Intermec (b)		5,964
		Bar Code & Wireless LAN Systems
	99,000	Zebra Technologies (b)		3,382
		Bar Code Printers
	100,000	Belden CDT		3,305
		Specialty Cable
	424,100	Seachange International (b)		2,952
		Systems for Video On Demand & Ad Insertion

Number of Shares			Value (000)
	40,000	Rogers (b)	$	2,254
		PCB Laminates & High-performance Foams
	90,000	Netgear (b)		1,949
		Networking Products for Small Business & Home
				59,564
		>Telecommunications Equipment: 1.7%
	1,525,000	Tellabs (b)		20,298
		Telecommunications Equipment
	310,000	Andrew (b)		2,746
		Wireless Infrastructure Equipment
	323,500	Symmetricom (b)		2,287
		Network Timing & Synchronization Devices
				25,331
		>Semiconductors and Related Equipment: 1.5%
	1,050,000	Entegris (b)		10,006
		Semiconductor Wafer Shipping & Handling Products
	683,490	Integrated Device Technology (b)		9,692
		Communications Semiconductors
	70,000	Littelfuse (b)		2,407
		Little Fuses
				22,105
		>Financial Processors: 1.3%
	393,280	Global Payments		19,094
		Credit Card Processor
		>Business Information and Marketing Services: 1.2%
	530,000	Ceridian (b)		12,953
		HR Services & Payment Processing
	44,000	Getty Images (b)		2,794
		Photographs for Publications & Electronic Media
	98,300	Navigant Consulting (b)		2,226
		Financial Consulting Firm
				17,973
		>Telephone Services: 1.2%
	1,086,000	Time Warner Telecom (b)		16,127
		Fiber Optic Telephone/Data Service Provider
	50,000	Commonwealth Telephone		1,658
		Rural Phone Franchises & Competing Telco
				17,785
		>Internet Related: 1.0%
	980,000	CNET Networks (b)		7,820
		Internet Advertising on Niche Websites
	460,000	ValueClick (b)		7,061
		Internet Advertising
				14,881
		>Instrumentation: 1.0%
	140,000	Mettler Toledo (b)		8,480
		Laboratory Equipment
	125,000	Trimble Navigation (b)		5,580
		GPS-Based Instruments
				14,060

Columbia Acorn USA

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Radio: 0.9%
	511,100	Salem Communications (b)	$	6,650
		Radio Stations for Religious Programming
	705,500	Spanish Broadcasting System (b)		3,605
		Spanish Language Radio Stations
	300,000	Saga Communications (b)		2,718
		Radio Stations in Small & Mid Sized Cities
				12,973
		>Computer Services: 0.8%
	1,005,500	AnswerThink Consulting (b)		4,052
		IT Integration & Best Practice Research
	786,000	RCM Technologies (b)(c)		3,946
		Technology & Engineering Services
	95,000	SRA International (b)		2,530
		Government IT Services
	235,000	Igate Capital (b)		1,502
		IT & BPO Outsourcing Services
				12,030
		>CATV: 0.8%
	2,580,000	Gemstar-TV Guide International (b)		9,082
		TV Program Guides & CATV Programming
	140,000	Discovery Holding (b)		2,048
		CATV Programming
				11,130
		>TV Broadcasting: 0.7%
	1,125,000	Entravision Communications (b)		9,641
		Spanish Language TV, Radio & Outdoor
	138,500	Gray Television		802
		Mid Market Affiliated TV Stations
				10,443
		>Gaming Equipment: 0.4%
	200,000	Bally Technologies (b)		3,294
		Slot Machines & Software
	98,500	Shuffle Master (b)		3,229
		Card Shufflers & Casino Games
				6,523
		>Television Programming: 0.3%
	460,000	Lions Gate Entertainment (b)		3,933
		Film & TV Studio
		>Contract Manufacturing: 0.2%
	105,000	Plexus (b)		3,592
		Electronic Manufacturing Services
		>Publishing: 0.0%
	13,850	Triple Crown Media (b)		120
		Newspapers, Paging & Collegiate Sports Marketing
		Information: Total		458,434
Consumer Goods/Services: 17.5%
		>Retail: 5.9%
	398,000	Abercrombie & Fitch		22,061
		Teen Apparel Retailer
	486,250	Christopher & Banks		14,101
		Women's Apparel Retailer

Number of Shares			Value (000)
	608,000	Petco Animal Supplies (b)	$	12,421
		Pet Supplies & Services
	224,500	Ann Taylor Stores (b)		9,739
		Women's Apparel Retailer
	353,000	Chico's FAS (b)		9,524
		Women's Specialty Retail
	203,000	Michaels Stores		8,372
		Craft & Hobby Specialty Retailer
	130,000	Aeropostale (b)		3,756
		Mall-Based Teen Retailer
	125,000	J Crew Group (b)		3,431
		Multi-Channel Branded Retailer
	95,000	Genesco (b)		3,218
		Multi-Concept Branded Footwear Retailer
				86,623
		>Apparel: 3.9%
	634,200	Oxford Industries		24,994
		Branded & Private Label Apparel
	545,200	Carter's (b)		14,410
		Children's Branded Apparel
	675,200	True Religion Apparel (b)		11,951
		Premium Denim
	222,200	Coach (b)		6,644
		Designer & Retailer of Branded Leather Accessories
				57,999
		>Other Consumer Services: 2.4%
	416,000	ITT Educational Services (b)		27,377
		Post-secondary Degree Programs
	387,700	Central Parking		6,203
		Owner, Operator, Manager of Parking Lots & Garages
	60,000	Weight Watchers		2,453
		Weight Loss Programs
				36,033
		>Leisure Products: 1.9%
	301,300	International Speedway Motors		13,971
		Largest Motorsports Racetrack Owner & Operator
	195,500	Speedway Motorsports		7,378
		Motorsport Racetrack Owner & Operator
	106,000	Polaris Industries		4,590
		Leisure Vehicles & Related Products
	195,000	Callaway Golf		2,533
		Premium Golf Clubs & Balls
				28,472
		>Nondurables: 1.5%
	496,400	Scotts Miracle-Gro		21,008
		Consumer Lawn & Garden Products
	100,000	Prestige Brands (b)		997
		OTC, Household & Personal Care Products
				22,005
		>Restaurants: 1.0%
	337,500	Sonic (b)		7,017
		Quick Service Restaurant
	163,800	Red Robin Gourmet Burgers (b)		6,971
		Casual Dining Restaurant
				13,988

1-800-922-6769

Number of Shares			Value (000)
		>Furniture and Textiles: 0.6%
	106,000	HNI	$	4,807
		Office Furniture & Fireplaces
	90,000	Herman Miller		2,319
		Office Furniture
	20,000	Mohawk Industries (b)		1,407
		Carpet & Flooring
				8,533
		>Travel: 0.2%
	45,000	Vail Resorts (b)		1,670
		Ski Resort Operator & Developer
	13,200	Kerzner International (Bahamas) (b)		1,046
		Destination Resorts & Casinos
				2,716
		>Other Durable Goods (includes auto related): 0.1%
	40,000	Cavco Industries (b)		1,778
		Higher End Manufactured Homes
		Consumer Goods/Services: Total		258,147
Health Care: 12.6%
		>Health Care Services: 4.3%
	550,000	United Surgical Partners (b)		16,539
		Outpatient Surgery Center
	210,000	LCA-Vision		11,111
		Lasik Surgery Centers
	291,800	Lincare Holdings (b)		11,042
		Home Healthcare Services
	199,875	Coventry Health Care (b)		10,981
		HMO
	258,000	Charles River Laboratories (b)		9,494
		Pharmaceutical Research
	175,000	PRA International (b)		3,897
		Contract Research Organization
				63,064
		>Medical Equipment: 3.8%
	577,400	Edwards Lifesciences (b)		26,231
		Heart Valves
	380,000	PSS World Medical (b)		6,707
		Medical Supplies Distributor
	220,000	Viasys Healthcare (b)		5,632
		Respiratory & Neurology Medical Equipment
	105,000	Vital Signs		5,201
		Anesthesia, Respiratory & Sleep Products
	94,171	Advanced Medical Optics (b)		4,774
		Medical Devices for Eye Care
	165,000	Intermagnetics General (b)		4,452
		MRI Equipment
	104,000	Arrow International		3,418
		Disposable Catheters
				56,415
		>Hospital/Laboratory Supplies: 3.1%
	547,400	Serologicals (b)		17,210
		Blood Collection & Antibody Production
	270,700	ICU Medical (b)		11,434
		Intravenous Therapy Products

Number of Shares			Value (000)
	146,200	Diagnostic Products	$	8,504
		Immunodiagnostic Kits
	158,300	Techne (b)		8,061
		Cytokines, Antibodies, other Reagents for Life Sciences
				45,209
		>Biotechnology/Drug Delivery: 1.4%
	360,000	Nektar Therapeutics (b)		6,602
		Drug Delivery Technologies
	293,000	Intermune (b)		4,820
		Drugs for Hepatitis C, Pulmonary Fibrosis & Cancer
	455,000	Ligand Pharmaceuticals (b)		3,845
		Drugs for Pain, Cancer, Osteoporosis, Diabetes
	235,000	Exelixis (b)		2,362
		Treatments for Cancer & Metabolic Disorders
	235,000	Decode Genetics (b)		1,455
		Drugs for Heart Attack, Asthma & Vascular Disease
	100,000	Momenta Pharmaceuticals (b)		1,271
		Sugar Analysis Technology for Drug Design
	375,000	Locus Discovery, Series D. Pfd. (d)		102
		High Throughput Rational Drug Design
	363,636	Metabolex, Series F (d)		84
		Drugs for Diabetes
				20,541
		Health Care: Total		185,229
Industrial Goods/Services: 11.1%
		>Machinery: 6.5%
	580,300	Esco Technologies (b)		31,017
		Automatic Electric Meter Readers
	673,600	Pentair		23,030
		Pumps, Water Treatment & Tools
	373,600	Nordson		18,373
		Dispensing Systems for Adhesives & Coatings
	319,800	Donaldson		10,832
		Industrial Air Filtration
	110,000	Ametek		5,212
		Aerospace/Industrial Instruments
	189,900	K&F Industries Holdings (b)		3,367
		Aircraft Wheels, Brakes & Fuel Tank Bladders
	132,000	Goodman Global (b)		2,004
		HVAC Equipment Manufacturer
	50,000	Kaydon		1,866
		Specialized Friction & Motion Control Products
				95,701
		>Electrical Components: 1.9%
	376,000	Genlyte Group (b)		27,233
		Commercial Lighting Fixtures
		>Construction: 0.9%
	204,050	Florida Rock Industries		10,135
		Aggregates & Concrete
	100,000	Simpson Manufacturing		3,605
		Wall Joint Maker
				13,740

Columbia Acorn USA

>Statement of Investments (Unaudited), continued

Number of Shares			Value (000)
		>Specialty Chemicals: 0.5%
	357,500	Spartech	$	8,080
		Plastics Distribution & Compounding
		>Outsourcing Services: 0.5%
	400,000	Quanta Services (b)		6,932
		Electrical & Telecom Construction Services
		>Waste Management: 0.5%
	187,250	Waste Connections (b)		6,816
		Solid Waste Management
		>Industrial Distribution: 0.2%
	113,000	NuCo2 (b)		2,717
		Bulk Co2 Gas Distribution to Restaurants
		>Other Industrial Services: 0.1%
	63,000	UTI Worldwide		1,589
		Global Logistics & Freight Forwarding
		Industrial Goods/Services: Total		162,808
Energy/Minerals: 9.4%
		>Oil Services: 4.9%
	401,700	FMC Technologies (b)		27,099
		Oil & Gas Well Head Manufacturer
	535,000	Chicago Bridge & Iron		12,920
		Engineering & Construction for Petrochemicals & LNG
	311,000	Pride International (b)		9,713
		Offshore Drilling Contractor
	152,000	Atwood Oceanics (b)		7,539
		Contract Drilling
	355,000	Hanover Compressor (b)		6,667
		Natural Gas Compressor Rental & Fabrications
	76,500	Carbo Ceramics		3,758
		Natural Gas Well Stimulants
	155,000	Key Energy Services (b)		2,364
		Well Workover Services
	350,900	Newpark Resources (b)		2,158
		Drilling Fluid Services
	11,000	Helmerich & Payne		663
		Contract Driller
				72,881
		>Oil and Gas Producers: 3.6%
	525,000	Quicksilver Resources (b)		19,325
		Natural Gas & Coal Seam Gas Producer
	282,600	Western Gas Resources		16,914
		Oil & Coal Seam Gas Producer
	208,400	Southwestern Energy (b)		6,494
		Natural Gas Producer
	450,000	Vaalco Energy (b)		4,392
		Oil & Gas Producer
	111,200	Equitable Resources		3,725
		Natural Gas Producer & Utility
	92,000	McMoran Exploration (b)		1,619
		Natural Gas Producer & Developer
				52,469

Number of Shares			Value (000)
		>Other Resources: 0.5%
	242,000	Layne Christensen (b)	$	6,861
		Oil & Gas Producer/Engineering & Construction/Contract Drilling
		>Oil Refining/Marketing/Distribution: 0.4%
	155,000	Atmos Energy		4,326
		Dallas Natural Gas Utility
	50,250	Oneok		1,710
		Natural Gas Distribution, Pipeline, Processing & Trading
				6,036
		Energy/Minerals: Total		138,247
Finance: 7.5%
		>Finance Companies: 3.4%
	1,121,500	AmeriCredit (b)		31,312
		Auto Lending
	520,200	World Acceptance (b)		18,478
		Personal Loans
				49,790
		>Insurance: 2.4%
	664,500	HCC Insurance Holdings		19,563
		Specialty Insurance
	14,000	Markel (b)		4,858
		Specialty Insurance
	105,000	Philadelphia Consolidated Holding (b)		3,188
		Specialty Insurance
	87,000	Delphi Financial Group		3,163
		Group Employee Benefit Products & Services
	75,000	Endurance Specialty Holdings		2,400
		Commercial Lines Insurance/Reinsurance
	91,000	United America Indemnity (b)		1,896
		Specialty Insurance
	1,600	Eastern Insurance Holdings (b)		20
		Workers Comp & Specialty Insurance
				35,088
		>Banks: 1.4%
	239,500	TCF Financial		6,335
		Great Lakes Bank
	212,756	Chittenden		5,500
		Vermont & Western Massachusetts Banks
	145,000	Greene County Bancshares		4,489
		Tennessee Bank
	94,000	Associated Banc-Corp		2,964
		Midwest Bank
	20,000	First Financial Bankshares		731
		West Texas Bank
	30,000	West Bancorporation		560
		Des Moines Commercial Bank
				20,579
		>Savings and Loans: 0.3%
	141,400	Anchor Bancorp Wisconsin		4,266
		Wisconsin Thrift
		Finance: Total		109,723

1-800-922-6769

Number of Shares or Principal Amount			Value (000)
Other Industries: 2.2%
		>Real Estate: 1.6%
	560,000	DiamondRock Hospitality	$	8,293
		Hotel Owner
	350,000	Highland Hospitality		4,928
		Hotel Owner
	77,500	Gaylord Entertainment (b)		3,382
		Convention Hotels
	150,000	Kite Realty Group		2,339
		Community Shopping Centers
	90,000	American Campus Communities		2,237
		Student Housing
	110,500	Crescent Real Estate Equities		2,051
		Class 'A' Office Buildings
				23,230
		>Transportation/Regulated Utilities: 0.6%
	424,720	Heartland Express		7,598
		Regional Trucker
	97,500	Northeast Utilities		2,015
		Utility
				9,613
		Other Industries: Total		32,843
		Total Common Stocks: 91.5% (Cost: $963,933)		1,345,431
Short-Term Obligations: 8.6%
$	65,000	Conocophillips 5.30% Due 7/03/06 - 7/06/06		64,965
	32,000	Countrywide Financial Funding 5.30% Due 7/03/06		31,972
	26,000	Verizon Global Funding 5.30% Due 7/05/06		25,985
	2,797	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/3/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 5/22/08 market value $2,855 (repurchase proceeds: $2,798)		2,797
		(Amortized Cost: $125,719)		125,719
	Total Investments: 100.1% (Cost: $1,089,652)(a)			1,471,150
	Cash and Other Assets Less Liabilities: (0.1%)			(817	)
	Total Net Assets: 100%		$	1,470,333

Columbia Acorn USA

>Statement of Investments (Unaudited), continued

>Notes to Statement of Investments (in thousands)

(b) Non-income producing security.

RCM Technologies

6.67

Dividend Income	$	—
Net realized gain or loss		—
Change in unrealized gain or loss		(63	)
Purchases		—
Proceeds from sales		—

Additional information on these securities is as follows:

Security	Acquisition Dates	Shares		Cost (000)		Value (000)
Locus Discovery, Series D, Pfd.	09/05/01		375,000	$	1,500	$	102
Metabolex, Series F	05/11/00		363,636		2,000		84
				$	3,500	$	186

1-800-922-6769

Columbia Acorn International Select

>Major Portfolio Changes in the Second Quarter (Unaudited)

	Number of Shares
	03/31/06		06/30/06
Additions
Europe
>Ireland
Anglo Irish Bank		174,000		265,000
Bank of Ireland		245,000		280,000
C&C Group		170,000		500,000
>Switzerland
Synthes		25,000		30,000
>Germany
Depfa Bank		185,000		215,000
>Sweden
Hexagon		0		32,000
Tele2		160,000		255,000
>Czech Republic
Komercni Banka		10,300		15,300
>Netherlands
USG People		0		17,000
Asia
>Japan
Hoya		90,000		110,000
Kansai Paint		80,000		280,000
Other Countries
>Canada
Alliance Atlantis Communication		0		72,000
Potash		30,700		35,000
>United States
Atwood Oceanics		0		60,800

	Number of Shares
	03/31/06		06/30/06
Sales
Europe
>Switzerland
BKW Energie		12,100		2,500
>Sweden
Gambro		320,200		0
>Norway
Orkla		47,000		0
Asia
>Japan
Ito En		76,000		36,000
Shimano		130,000		5,600
Ushio		145,000		85,000
Other Countries
>Canada
Kinross Gold		311,000		111,000
Talisman Energy		78,000		0
(includes the effect of a 3 for 1 stock split)
Latin America
>Argentina
Tenaris		29,500		0
(includes the effect of a 5 for 1 stock split)

Columbia Acorn International Select

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares			Value (000)
		Common Stocks: 93.6%
Europe: 55.0%
		>Ireland: 15.9%
	280,000	Bank of Ireland	$	5,012
		Irish Commercial Bank
	500,000	C&C Group		4,342
		Beverage Company
	265,000	Anglo Irish Bank		4,129
		Small Business & Middle Market Banking
	220,000	IAWS Group		3,879
		Baked Goods
	125,000	Grafton Group		1,574
		Builders Materials Wholesaling & Do-it-yourself Retailing
				18,936
		>Switzerland: 10.6%
	30,000	Synthes		3,614
		Products for Orthopedic Surgery
	42,500	Kuehne & Nagel		3,094
		Freight Forwarding/Logistics
	2,400	Geberit		2,773
		Plumbing Supplies
	10,250	Swatch Group		1,729
		Watch & Electronics Manufacturer
	23,000	Schindler		1,191
		Elevator Manufacturer & Service Provider
	2,500	BKW Energie		219
		Electric Utility
				12,620
		>France: 7.4%
	24,200	Neopost		2,755
		Postage Meter Machines
	182,300	SES Global		2,597
		Satellite Broadcasting Services
	20,000	Essilor International		2,011
		Eyeglass Lenses
	18,000	Imerys		1,438
		Industrial Minerals Producer
				8,801
		>Germany: 6.4%
	215,000	Depfa Bank		3,564
		Investment Banker to Public Authorities
	3,300	Porsche		3,184
		Specialty Automobile Manufacturer
	6,000	Deutsche Boerse		816
		Trading, Clearing, Settlement Services for Financial Markets
				7,564
		>United Kingdom: 3.3%
	215,000	Northern Rock		3,971
		Lowest Cost Mortgage Bank in UK
		>Sweden: 3.1%
	255,000	Tele2		2,573
		European Mobile Operator & Services Reseller
	32,000	Hexagon		1,165
		Measurement Equipment & Polymers
				3,738

Number of Shares			Value (000)
		>Denmark: 2.8%
	50,000	Novozymes	$	3,370
		Industrial Enzymes
		>Spain: 2.5%
	88,000	Red Electrica		3,034
		Spanish Power Grid
		>Czech Republic: 1.9%
	15,300	Komercni Banka		2,239
		Leading Czech Universal Bank
		>Netherlands: 1.1%
	17,000	USG People		1,301
		Temporary Staffing Services
		Europe: Total		65,574
Asia: 28.2%
		>Japan: 24.1%
	76,000	Daito Trust Construction		4,226
		Apartment Builder
	110,000	Hoya		3,932
		Opto-Electrical Components & Eyeglass Lenses
	5,299	Jupiter Telecommunications (b)		3,673
		Largest Cable Service Provider in Japan
	55,000	Aeon Mall		2,308
		Suburban Shopping Mall Developer, Owner & Operator
	280,000	Kansai Paint		2,240
		Paint Producer in Japan, India, China & Southeast Asia
	85,000	JSR		2,157
		Films & Chemicals for LCD Screens & Electronics
	30,000	USS		1,986
		Used Car Auctioneer
	1,800	Sparx Asset Management		1,881
		Fund Management
	420	Kenedix		1,819
		Real Estate Investment Management
	85,000	Ushio		1,800
		Industrial Light Sources
	36,000	Ito En		1,321
		Bottled Tea & Other Beverages
	199,800	Hiroshima Bank		1,222
		Regional Bank
	5,600	Shimano		172
		Bicycle Components & Fishing Tackle
				28,737
		>Hong Kong: 3.3%
	610,000	Hong Kong Exchanges and Clearing		3,920
		Hong Kong Equity & Derivatives Market Operator

1-800-922-6769

Number of Shares or Principal Amount			Value (000)
		>Singapore: 0.8%
	1,000,000	Comfort Del Gro	$	964
		Taxi & Mass Transit Service
		Asia: Total		33,621
Other Countries: 10.4%
		>Canada: 6.8%
	35,000	Potash		3,009
		World's Largest Producer of Potash
	72,000	Alliance Atlantis Communication (b)		2,109
		CATV Channels, TV/Movie Production/Distribution
	100,000	Rona (b)		1,796
		Leading Canadian DIY Retailer
	111,000	Kinross Gold (b)		1,210
		Gold Mining
				8,124
		>United States: 2.6%
	60,800	Atwood Oceanics (b)		3,016
		Contract Drilling
		>South Africa: 1.0%
	6,500	Impala Platinum Holdings		1,195
		Platinum Group Metals Mining & Refining
		Other Countries: Total		12,335
		Total Common Stocks: 93.6% (Cost: $90,604)		111,530
Short-Term Obligation: 6.2%
$	7,418	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/03/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 5/22/08 market value $7,570 (repurchase proceeds: $7,421)		7,418
		(Amortized Cost: $7,418)
	Total Investments: 99.8% (Cost: $98,022)(a)(c)			118,948
	Cash and Other Assets Less Liabilities: 0.2%			230
	Total Net Assets: 100%		$	119,178

Columbia Acorn International Select

>Statement of Investments (Unaudited), continued

>Notes to Statement of Investments (in thousands)

(b) Non-income producing security.

Currency	Value		% of Total Net Assets
Euro	$	39,637		33.3	%
Japanese Yen		28,737		24.1
US Dollar		13,443		11.3
Swiss Franc		12,620		10.6
Other currencies less than 5% of total net assets		24,511		20.5
	$	118,948		99.8	%

1-800-922-6769

Columbia Acorn International Select

>Portfolio Diversification

At June 30, 2006, the Fund's portfolio investments as a percent of net assets was diversified as follows:

	Value (000)		Percent
>Industrial Goods/Services
Specialty Chemicals	$	7,768		6.5	%
Construction		6,999		5.9
Other Industrial Services		4,285		3.6
Machinery		2,755		2.3
Electrical Components		1,800		1.5
Industrial Distribution		1,573		1.3
Industrial Materials		1,438		1.2
Outsourcing Services		1,301		1.1
Conglomerates		1,165		1.0
		29,084		24.4
>Finance
Banks		20,136		16.9
Money Management		1,881		1.6
		22,017		18.5
>Consumer Goods/Services
Beverage		5,663		4.8
Durables Goods		5,085		4.3
Retail		4,104		3.4
Food		3,879		3.2
Consumer Goods Distribution		1,986		1.7
		20,717		17.4
>Information
Financial Processors		4,736		4.0
Semiconductors & Related Equipment		3,933		3.3
Cable Television		3,673		3.1
Satellite Broadcasting		2,597		2.2
Telephone Services		2,573		2.1
Television Programming		2,109		1.7
		19,621		16.4

	Value (000)		Percent
>Energy/Minerals
Mining	$	5,414		4.6	%
Oil/Gas Producers		3,015		2.5
		8,429		7.1
>Other Industries
Regulated Utilities		3,253		2.8
Real Estate		1,819		1.5
Transportation		964		0.8
		6,036		5.1
>Health Care
Medical Equipment		5,626		4.7
		5,626		4.7
Total Common Stocks		111,530		93.6
Short-Term Obligation		7,418		6.2
Total Investments		118,948		99.8
Cash and Other Assets Less Liabilities		230		0.2
Total Net Assets	$	119,178		100.0	%

Columbia Acorn Select

>Major Portfolio Changes in the Second Quarter (Unaudited)

	Number of Shares
	03/31/06		06/30/06
Additions
Consumer Goods/Services
Coach		1,400,000		1,506,000
Expedia		1,200,000		3,300,000
Petco Animal Supplies		1,300,000		1,350,000
Information
Avid Technology		1,600,000		1,650,000
Liberty Global, Series A		1,000,000		1,139,734
Novell		5,000,000		5,500,000
Sanmina-SCI		0		4,000,000
Tellabs		9,600,000		9,750,000
Industrial Goods/Services
Worthington Industries		2,150,000		2,250,000
Energy/Minerals
Potash (Canada)		400,000		480,000
UrAsia Energy (Canada)		1,900,000		2,800,000
Finance
Janus Capital Group		2,500,000		3,200,000

	Number of Shares
	03/31/06		06/30/06
Sales
Information
IAC/Interactive Corp		544,000		0
Liberty Global, Series C		3,400,000		3,232,702
Tektronix		1,400,000		0
Tribune Company		803,700		702,900
Finance
Associated Banc-Corp		750,000		0
Health Care
Coventry Health Care		900,000		0

1-800-922-6769

Columbia Acorn Select

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares			Value (000)
		Common Stocks: 94.6%
Consumer Goods/Services: 29.4%
		>Consumer Services: 11.8%
	1,625,000	ITT Educational Services (b)	$	106,941
		Post-secondary Degree Programs
	3,500,000	Safeway		91,000
		Supermarkets
	728,000	Weight Watchers		29,768
		Weight Loss Programs
				227,709
		>Retail: 7.9%
	1,400,000	Abercrombie & Fitch		77,602
		Teen Apparel Retailer
	845,000	Costco Wholesale		48,275
		Warehouse Superstores
	1,350,000	Petco Animal Supplies (b)		27,580
		Pet Supplies & Services
				153,457
		>Leisure Products: 4.9%
	1,100,000	Harley-Davidson		60,379
		Motorcycles & Related Merchandise
	740,000	International Speedway Motors		34,314
		Largest Motorsports Racetrack Owner & Operator
				94,693
		>Travel: 2.5%
	3,300,000	Expedia (b)		49,401
		Online Travel Services Company
		>Apparel: 2.3%
	1,506,000	Coach (b)		45,029
		Designer & Retailer of Branded Leather Accessories
		Consumer Goods/Services: Total		570,289
Information: 29.0%
		>Telecommunications Equipment: 6.7%
	9,750,000	Tellabs (b)		129,773
		Telecommunications Equipment
		>CATV: 6.6%
	3,232,702	Liberty Global, Series C (b)		66,497
	1,139,734	Liberty Global, Series A (b)		24,504
		CATV Holding Company
	2,500,000	Discovery Holding (b)		36,575
		CATV Programming
				127,576
		>Business Software: 4.7%
	1,650,000	Avid Technology (b)		54,995
		Digital Nonlinear Editing Software & Systems
	5,500,000	Novell (b)		36,465
		Directory, Operating System & Identity Management Software
				91,460
		>Mobile Communications: 3.7%
	2,300,000	American Tower (b)		71,575
		Communications Towers in USA & Mexico

Number of Shares			Value (000)
		>Internet Related: 3.0%
	9,600,000	Skillsoft Publishing (b)(c)	$	58,752
		Web-based Learning Solutions (E-Learning)
		>Financial Processors: 1.8%
	729,500	SEI Investments		35,658
		Mutual Fund Administration & Investment Management
		>Publishing: 1.2%
	702,900	Tribune Company		22,795
		Newspapers & TV Stations
		>Contract Manufacturing: 1.0%
	4,000,000	Sanmina-SCI (b)		18,400
		Backplane & Electronic Manufacturing Services
		>Computer Services: 0.3%
	1,367,000	AnswerThink Consulting (b)		5,509
		IT Integration & Best Practice Research
		Information: Total		561,498
Industrial Goods/Services: 13.7%
		>Other Industrial Services: 3.8%
	1,322,000	Expeditors International of Washington		74,045
		International Freight Forwarder
		>Outsourcing Services: 2.7%
	3,030,000	Quanta Services (b)		52,510
		Electrical & Telecom Construction Services
		>Steel: 2.5%
	2,250,000	Worthington Industries		47,138
		Steel Processing
		>Waste Management: 2.4%
	1,300,000	Waste Management		46,644
		U.S. Garbage Collection & Disposal
		>Industrial Materials: 2.3%
	1,125,000	Mine Safety Appliances		45,225
		Safety Equipment
		Industrial Goods/Services: Total		265,562
Energy/Minerals: 11.4%
		>Mining: 6.2%
	31,500,000	UrAsia Energy (Canada) (b)(c)		79,011
		Uranium Mining in Kazakhstan
	480,000	Potash (Canada)		41,266
		World's Largest Producer of Potash
				120,277

Columbia Acorn Select

>Statement of Investments (Unaudited), continued

Number of Shares or Principal Amount			Value (000)
		>Oil Services: 5.2%
	1,950,000	Pride International (b)	$	60,899
		Contract Drilling
	600,000	FMC Technologies (b)		40,475
		Oil & Gas Well Head Manufacturer
				101,374
		Energy/Minerals: Total		221,651
Finance: 9.3%
		>Money Management: 5.2%
	3,200,000	Janus Capital Group		57,280
		Manages Mutual Funds
	975,000	Nuveen Investments		41,974
		Specialty Mutual Funds
				99,254
		>Insurance: 4.1%
	1,800,000	Conseco (b)		41,580
		Life, Long Term Care & Medical Supplement Insurance
	112,000	Markel (b)		38,865
		Specialty Insurance
				80,445
		Finance: Total		179,699
Health Care: 1.8%
		>Health Care Services: 1.8%
	910,000	Lincare Holdings (b)		34,434
		Home Health Care Services
		Health Care: Total		34,434
		Total Common Stock: 94.6% (Cost: $1,388,372)		1,833,133
Short-Term Obligations: 3.2%
$	30,000	Conocophillips 5.30% Due 7/03/06		29,987
	27,000	Countrywide Financial Funding 5.25% Due 7/05/06		26,976
	8,784	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/3/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 5/22/08 market value $4,880 (repurchase proceeds: $4,786)		4,784
		(Amortized Cost: $61,747)		61,747
	Total Investments: 97.8% (Cost: $1,450,119)(a)			1,894,880
	Cash and Other Assets Less Liabilities: 2.2%			42,833
	Total Net Assets: 100%		$	1,937,713

1-800-922-6769

>Notes to Statement of Investments (in thousands)

(b) Non-income producing security.

Skillsoft Publishing					8.88	%
UrAsia Energy (Canada)					6.56	%

Dividend Income	$	—
Net realized gain or loss		—
Change in unrealized gain or loss		24,788
Purchases		6,039
Proceeds from sales		—

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1-800-922-6769

Columbia Acorn Family of Funds

> Statements of Assets and Liabilities

> Statements of Operations

> Statements of Changes in Net Assets

> Financial Highlights

> Notes to Financial Statements

Columbia Acorn Family of Funds

>Statements of Assets and Liabilities (Unaudited)

June 30, 2006	Columbia Acorn Fund			Columbia Acorn International		Columbia Acorn USA			Columbia Acorn International Select			Columbia Acorn Select
(in thousands)
Assets:
Unaffiliated investments, at cost	$	9,452,305		$	2,456,244	$	1,084,016		$	98,022		$	1,339,233
Affiliated investments, at cost (See Note 4)		1,819,627			29,676		5,636			—			110,886
Unaffiliated investments, at value	$	14,993,693		$	3,550,552	$	1,467,204		$	118,948		$	1,757,117
Affiliated investments, at value (See Note 4)		2,934,084			21,869		3,946			—			137,763
Cash		2,056			1		13			1			1
Foreign currency (cost: Columbia Acorn Fund $5,941; Columbia Acorn International $5,019; Columbia Acorn International Select $200; Columbia Acorn Select $*)		6,049			5,077		—			203			—	*
Receivable for:
Investments sold		28,918			8,075		1,587			343			45,986
Fund shares sold		24,568			8,551		2,822			117			2,178
Dividends and interest		8,609			6,066		400			197			342
Foreign tax reclaims		793			1,042		2			36			—
Deferred Trustees' Compensation Investments		1,927			538		136			—			—
Other assets		—			122		90			2			—
Total Assets		18,000,697			3,601,893		1,476,200			119,847			1,943,387
Liabilities:
Payable for:
Investments purchased		53,778			711		3,405			384			76
Fund shares redeemed		14,600			1,357		978			97			3,377
Management fee		9,220			2,220		1,024			90			1,270
Administration fee		588			117		48			4			64
12b-1 Service & Distribution fees		2,923			157		132			11			442
Reports to shareholders		633			205		90			36			230
Deferred Trustees' fees		1,927			538		136			12			47
Transfer agent fees		600			80		36			6			135
Trustees' fees		4			—		—			—	*		6
Audit fee		32			34		18			19			18
Custody fees		210			172		—			10			—
Other liabilities		106			—		—			—			9
Total Liabilities		84,621			5,591		5,867			669			5,674
Net Assets	$	17,916,076		$	3,596,302	$	1,470,333		$	119,178		$	1,937,713
Composition of Net Assets:
Paid in capital	$	10,598,812		$	2,229,793	$	1,096,188		$	111,933		$	1,468,574
Undistributed (overdistributed) net investment income (Accumulated net investment loss)		(6,560	)		4,339		(1,371	)		(357	)		(15,027	)
Accumulated net realized gain (loss)		667,823			275,512		(6,049	)		(13,330	)		39,405
Net unrealized appreciation (depreciation) on:
Investments		6,655,845			1,086,501		381,498			20,926			444,761
Foreign currency translations		156			157		67			6			—	*
Net Assets	$	17,916,076		$	3,596,302	$	1,470,333		$	119,178		$	1,937,713
Net asset value per share – Class A (a)	$	28.81		$	37.33	$	26.96		$	22.95		$	23.55
(Net assets/shares)		($3,808,423/132,182)			($211,021/5,652)		($220,043/8,162)			($14,167/617)			($788,153/33,464)
Maximum offering price per share – Class A (b)	$	30.57		$	39.61	$	28.60		$	24.35		$	24.99
(Net asset value per share/front-end sales charge)		($28.81/0.9425)			($37.33/0.9425)		($26.96/0.9425)			($22.95/0.9425)			($23.55/0.9425)
Net asset value and offering price per share – Class B (a)	$	27.71		$	36.65	$	25.95		$	22.24		$	22.69
(Net assets/shares)		($1,406,504/50,764)			($82,345/2,247)		($67,649/2,607)			($7,910/356)			($203,596/8,973)
Net asset value and offering price per share – Class C (a)	$	27.66		$	36.61	$	25.92		$	22.23		$	22.66
(Net assets/shares)		($1,300,779/47,032)			($76,524/2,091)		($50,799/1,960)			($5,006/225)			($155,134/6,847)
Net asset value and offering price per share – Class Z (c)	$	29.49		$	37.58	$	27.52		$	23.16		$	23.87
(Net assets/shares)		($11,400,370/386,621)			($3,226,412/85,846)		($1,131,842/41,121)			($92,095/3,976)			($790,830/33,124)

(a) Redemption price per share is equal to net asset value less any applicable contingent deferred sales charge.

(b) On sales of $50,000 or more the offering price is reduced.

* Rounds to less than $500.

See accompanying notes to financial statements.

1-800-922-6769

Columbia Acorn Family of Funds

>Statements of Operations
For the Six Months Ended June 30, 2006 (Unaudited)

(in thousands)	Columbia Acorn Fund			Columbia Acorn International			Columbia Acorn USA			Columbia Acorn International Select			Columbia Acorn Select
Investment Income:
Dividend income	$	72,878		$	39,687		$	3,023		$	1,249		$	5,670
Dividend income from affiliates (See Note 4)		13,299			58			—			—			—
Interest income		28,493			6,484			3,409			100			1,399
		114,670			46,229			6,432			1,349			7,069
Foreign taxes withheld		(2,712	)		(3,643	)		(5	)		(105	)		(16	)
Total Investment Income		111,958			42,586			6,427			1,244			7,053
Expenses:
Management fee		57,105			13,306			6,073			521			7,840
Administration fee		3,643			701			287			23			391
12b-1 Service and Distribution fees:
Class A		4,680			241			250			15			984
Class B		6,192			355			307			32			890
Class C		6,533			335			235			23			780
Transfer agent fees:
Class A		1,007			69			57			8			326
Class B		1,048			74			59			10			211
Class C		596			33			25			4			111
Class Z		1,265			538			122			28			234
Custody fees		922			919			20			27			29
Trustees' fees		303			47			21			1			15
Registration & blue sky fees		167			128			76			42			106
Reports to shareholders		1,248			320			134			43			308
Compliance fees		259			48			20			2			27
Non-recurring costs (See Note 9)		84			16			7			1			9
Other expenses		364			87			43			30			52
Total expenses		85,416			17,217			7,736			810			12,313
Less custody fees paid indirectly		(60	)		(8	)		(2	)		—	*		(4	)
Less reimbursement of expenses by Investment Adviser		—			—			—			(2	)		—
Less fees waived by Transfer Agent		(817	)		(96	)		(48	)		(7	)		(170	)
Non-recurring costs reimbursed (See Note 9)		(84	)		(16	)		(7	)		(1	)		(9	)
Net Expenses		84,455			17,097			7,679			800			12,130
Net Investment Income (Loss)		27,503			25,489			(1,252	)		444			(5,077	)
Net Realized and Unrealized Gain (Loss) on Portfolio Positions:
Net realized gain (loss) on:
Unaffiliated investments		670,179			276,747			(3,184	)		12,297			39,660
Foreign currency transactions		265			(410	)		—			(18	)		13
Net realized gain (loss)		670,444			276,337			(3,184	)		12,279			39,673
Net change in net unrealized appreciation (depreciation) on:
Unaffiliated investments		(23,305	)		121,881			25,365			(378	)		35,008
Affiliated investments (See Note 4)		253,598			(10,121	)		(63	)		—			24,788
Foreign currency translations		126			14			67			7			—
Foreign capital gains tax		—			3			—			—			—
Net change in unrealized appreciation (depreciation)		230,419			111,777			25,369			(371	)		59,796
Net realized and unrealized gain		900,863			388,114			22,185			11,908			99,469
Net Increase in Net Assets resulting from Operations	$	928,366		$	413,603		$	20,933		$	12,352		$	94,392

* Rounds to less than $500.

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

>Statements of Changes in Net Assets

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA
Increase (Decrease) in Net Assets	(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,
(in thousands)	2006			2005			2006			2005			2006			2005
Operations:
Net investment income (loss)	$	27,503		$	49,723		$	25,489		$	24,670		$	(1,252	)	$	1,300
Net realized gain (loss) on investments and foreign currency transactions		670,444			890,559			276,337			203,167			(3,184	)		49,825
Net change in net unrealized appreciation (depreciation) on investments and foreign currency translations and foreign capital gains tax		230,419			898,946			111,777			258,860			25,369			75,612
Net Increase from Operations		928,366			1,839,228			413,603			486,697			20,933			126,737
Distributions Declared to Shareholders From:
Net investment income – Class A		—			(8,157	)		(1	)		(1,772	)		—			—
Net realized gain – Class A		(40,975	)		(177,617	)		(3,315	)		(4,275	)		(819	)		(7,747	)
Net investment income – Class B		—			—			—	*		(280	)		—			—
Net realized gain – Class B		(15,915	)		(81,483	)		(1,276	)		(2,334	)		(270	)		(3,824	)
Net investment income – Class C		—			—			(1	)		(171	)		—			—
Net realized gain – Class C		(14,668	)		(68,235	)		(1,189	)		(1,462	)		(194	)		(2,282	)
Net investment income – Class Z		—			(52,311	)		(6,544	)		(51,974	)		—			(1,613	)
Net realized gain – Class Z		(120,087	)		(547,733	)		(46,561	)		(81,064	)		(4,177	)		(43,227	)
Total Distribution to Shareholders		(191,645	)		(935,536	)		(58,887	)		(143,332	)		(5,460	)		(58,693	)
Share Transactions:
Subscriptions – Class A		659,206			912,797			88,963			66,630			72,214			66,241
Distributions reinvested – Class A		37,164			167,704			2,797			4,900			723			6,880
Redemptions – Class A		(385,545	)		(579,536	)		(38,125	)		(14,669	)		(23,405	)		(25,265	)
Net Increase – Class A		310,825			500,965			53,635			56,861			49,532			47,856
Subscriptions – Class B		16,838			49,025			10,985			17,173			850			4,001
Distributions reinvested – Class B		14,515			74,120			1,143			2,310			248			3,491
Redemptions – Class B		(107,477	)		(174,945	)		(11,978	)		(10,198	)		(7,678	)		(11,124	)
Net Increase (Decrease) – Class B		(76,124	)		(51,800	)		150			9,285			(6,580	)		(3,632	)
Subscriptions – Class C		105,355			171,533			33,664			15,891			12,391			8,047
Distributions reinvested – Class C		11,709			54,677			890			1,302			163			1,878
Redemptions – Class C		(85,492	)		(149,119	)		(10,292	)		(6,051	)		(4,935	)		(9,090	)
Net Increase (Decrease) – Class C		31,572			77,091			24,262			11,142			7,619			835
Subscriptions – Class Z		1,068,234			1,686,601			403,326			577,455			262,241			302,588
Distributions reinvested – Class Z		103,086			513,385			39,291			103,732			3,812			40,433
Redemptions – Class Z		(649,562	)		(1,080,069	)		(171,762	)		(284,340	)		(83,258	)		(105,312	)
Net Increase – Class Z		521,758			1,119,917			270,855			396,847			182,795			237,709
Net Increase from Share Transactions		788,031			1,646,173			348,902			474,135			233,366			282,768
Redemption Fees		—			—			107			65			—			—
Total Increase in Net Assets		1,524,752			2,549,865			703,725			817,565			248,839			350,812
Net Assets:
Beginning of period		16,391,324			13,841,459			2,892,577			2,075,012			1,221,494			870,682
End of period	$	17,916,076		$	16,391,324		$	3,596,302		$	2,892,577		$	1,470,333		$	1,221,494
Undistributed (Overdistributed) Net Investment Income or (Accumulated Net Investment Loss)	$	(6,560	)	$	(34,063	)	$	4,339		$	(14,604	)	$	(1,371	)	$	(119	)

	Columbia Acorn International Select						Columbia Acorn Select
Increase (Decrease) in Net Assets	(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,
(in thousands)	2006			2005			2006			2005
Operations:
Net investment income (loss)	$	444		$	431		$	(5,077	)	$	(7,333	)
Net realized gain (loss) on investments and foreign currency transactions		12,279			5,496			39,673			46,214
Net change in net unrealized appreciation (depreciation) on investments and foreign currency translations and foreign capital gains tax		(371	)		5,773			59,796			140,962
Net Increase from Operations		12,352			11,700			94,392			179,843
Distributions Declared to Shareholders From:
Net investment income – Class A		(2	)		(79	)		(788	)		—
Net realized gain – Class A		—			—			(2,891	)		(19,098	)
Net investment income – Class B		—			(46	)		—			—
Net realized gain – Class B		—			—			(780	)		(5,029	)
Net investment income – Class C		—	*		(24	)		—			—
Net realized gain – Class C		—			—			(593	)		(3,559	)
Net investment income – Class Z		(196	)		(888	)		(1,614	)		—
Net realized gain – Class Z		—			—			(2,827	)		(19,071	)
Total Distribution to Shareholders		(198	)		(1,037	)		(9,493	)		(46,757	)
Share Transactions:
Subscriptions – Class A		4,045			5,743			88,593			296,611
Distributions reinvested – Class A		2			71			3,419			17,770
Redemptions – Class A		(1,414	)		(1,004	)		(83,751	)		(143,717	)
Net Increase – Class A		2,633			4,810			8,261			170,664
Subscriptions – Class B		1,272			2,123			3,191			28,258
Distributions reinvested – Class B		—			41			697			4,510
Redemptions – Class B		(775	)		(1,480	)		(16,156	)		(26,292	)
Net Increase (Decrease) – Class B		497			684			(12,268	)		6,476
Subscriptions – Class C		950			1,655			11,122			48,457
Distributions reinvested – Class C		—	*		20			483			2,903
Redemptions – Class C		(522	)		(599	)		(12,280	)		(23,251	)
Net Increase (Decrease) – Class C		428			1,076			(675	)		28,109
Subscriptions – Class Z		12,943			25,890			135,599			333,604
Distributions reinvested – Class Z		99			582			3,108			13,462
Redemptions – Class Z		(4,579	)		(7,003	)		(68,526	)		(155,173	)
Net Increase – Class Z		8,463			19,469			70,181			191,893
Net Increase from Share Transactions		12,021			26,039			65,499			397,142
Redemption Fees		4			9			—			—
Total Increase in Net Assets		24,179			36,711			150,398			530,228
Net Assets:
Beginning of period		94,999			58,288			1,787,315			1,257,087
End of period	$	119,178		$	94,999		$	1,937,713		$	1,787,315
Undistributed (Overdistributed) Net Investment Income or (Accumulated Net Investment Loss)	$	(357	)	$	(603	)	$	(15,027	)	$	(7,548	)

* Rounds to less than $500.

See accompanying notes to financial statements.

1-800-922-6769

Columbia Acorn Family of Funds

>Statements of Changes in Net Assets, continued

	Columbia Acorn Fund						Columbia Acorn International						Columbia Acorn USA
Changes in Shares of Beneficial Interest:	(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,
(in thousands)	2006			2005			2006			2005			2006			2005
Subscriptions – Class A		22,554			34,302			2,347			2,150			2,619			2,559
Shares issued in reinvestment and capital gains – Class A		1,300			6,137			75			155			27			260
Less shares redeemed – Class A		(13,166	)		(21,923	)		(1,054	)		(476	)		(855	)		(990	)
Net Increase – Class A		10,688			18,516			1,368			1,829			1,791			1,829
Subscriptions – Class B		595			1,922			299			574			32			161
Shares issued in reinvestment and capital gains – Class B		528			2,814			31			73			9			137
Less shares redeemed – Class B		(3,813	)		(6,826	)		(332	)		(341	)		(291	)		(451	)
Net Increase (Decrease) – Class B		(2,690	)		(2,090	)		(2	)		306			(250	)		(153	)
Subscriptions – Class C		3,731			6,667			906			524			466			321
Shares issued in reinvestment and capital gains – Class C		427			2,077			24			41			6			74
Less shares redeemed – Class C		(3,039	)		(5,835	)		(287	)		(201	)		(186	)		(363	)
Net Increase (Decrease) – Class C		1,119			2,909			643			364			286			32
Subscriptions – Class Z		35,686			62,182			10,707			18,615			9,306			11,555
Shares issued in reinvestment and capital gains – Class Z		3,525			18,385			1,050			3,274			139			1,500
Less shares redeemed – Class Z		(21,759	)		(39,912	)		(4,553	)		(9,349	)		(2,974	)		(4,040	)
Net Increase – Class Z		17,452			40,655			7,204			12,540			6,471			9,015
Net Increase in Shares of Beneficial Interest		26,569			59,990			9,213			15,039			8,298			10,723

	Columbia Acorn International Select						Columbia Acorn Select
Changes in Shares of Beneficial Interest:	(Unaudited) Six months ended June 30,			Year ended December 31,			(Unaudited) Six months ended June 30,			Year ended December 31,
(in thousands)	2006			2005			2006			2005
Subscriptions – Class A		178			307			3,735			14,487
Shares issued in reinvestment and capital gains – Class A		—	*		4			146			802
Less shares redeemed – Class A		(63	)		(53	)		(3,535	)		(6,938	)
Net Increase – Class A		115			258			346			8,351
Subscriptions – Class B		58			118			139			1,441
Shares issued in reinvestment and capital gains – Class B		—			2			31			211
Less shares redeemed – Class B		(35	)		(81	)		(708	)		(1,313	)
Net Increase (Decrease) – Class B		23			39			(538	)		339
Subscriptions – Class C		43			92			486			2,455
Shares issued in reinvestment and capital gains – Class C		—			1			22			136
Less shares redeemed – Class C		(24	)		(33	)		(539	)		(1,172	)
Net Increase (Decrease) – Class C		19			60			(31	)		1,419
Subscriptions – Class Z		574			1,378			5,651			15,890
Shares issued in reinvestment and capital gains – Class Z		4			33			131			601
Less shares redeemed – Class Z		(204	)		(378	)		(2,851	)		(7,371	)
Net Increase – Class Z		374			1,033			2,931			9,120
Net Increase in Shares of Beneficial Interest		531			1,390			2,708			19,229

* Rounds to less than 500 shares.

See accompanying notes to financial statements.

1-800-922-6769

Columbia Acorn Family of Funds

>Financial Highlights

Columbia Acorn Fund

Class A Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	27.57		$	25.93		$	22.20		$	15.34		$	17.80		$	17.19
Income from Investment Operations
Net investment income (loss) (a)		0.04			0.07			(0.05	)		(0.07	)		(0.07	)		(0.05	)
Net realized and unrealized gain (loss)		1.51			3.20			4.69			6.95			(2.39	)		1.01
Total from Investment Operations		1.55			3.27			4.64			6.88			(2.46	)		0.96
Less Distributions Declared to Shareholders
From net investment income		—			(0.07	)		—			—			—			—
From net realized gains		(0.31	)		(1.56	)		(0.91	)		(0.02	)		—			(0.35	)
Total Distributions Declared to Shareholders		(0.31	)		(1.63	)		(0.91	)		(0.02	)		—			(0.35	)
Net Asset Value, End of Period	$	28.81		$	27.57		$	25.93		$	22.20		$	15.34		$	17.80
Total Return (b)		5.64	%(c)(d)		12.76	%(c)		21.05	%(c)		44.85	%		(13.82	)%		5.56	%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)		1.01	%(f)		1.03	%		1.20	%		1.33	%		1.42	%		1.42	%
Net investment income (loss) (e)		0.25	%(f)		0.28	%		(0.21	)%		(0.36	)%		(0.45	)%		(0.33	)%
Waiver/reimbursement		0.01	%(f)		0.02	%		0.02	%		—			—			—
Portfolio turnover rate		11	%(d)		16	%		20	%		10	%		13	%		20	%
Net assets at end of period (000's)	$	3,808,423		$	3,349,461		$	2,669,936		$	1,982,260		$	724,121		$	306,405

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Class B Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	26.61		$	25.19		$	21.75		$	15.13		$	17.67		$	17.17
Income from Investment Operations
Net investment loss (a)		(0.06	)		(0.11	)		(0.22	)		(0.18	)		(0.17	)		(0.16	)
Net realized and unrealized gain (loss)		1.47			3.09			4.57			6.82			(2.37	)		1.01
Total from Investment Operations		1.41			2.98			4.35			6.64			(2.54	)		0.85
Less Distributions Declared to Shareholders
From net realized gains		(0.31	)		(1.56	)		(0.91	)		(0.02	)		—			(0.35	)
Total Distributions Declared to Shareholders		(0.31	)		(1.56	)		(0.91	)		(0.02	)		—			(0.35	)
Net Asset Value, End of Period	$	27.71		$	26.61		$	25.19		$	21.75		$	15.13		$	17.67
Total Return (b)		5.32	%(c)(d)		11.98	%(c)		20.15	%(c)		43.89	%		(14.37	)%		4.92	%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)		1.70	%(f)		1.72	%		1.95	%		1.98	%		2.07	%		2.07	%
Net investment loss (e)		(0.45	)%(f)		(0.42	)%		(0.96	)%		(1.01	)%		(1.10	)%		(0.98	)%
Waiver/reimbursement		0.01	%(f)		0.02	%		0.02	%		—			—			—
Portfolio turnover rate		11	%(d)		16	%		20	%		10	%		13	%		20	%
Net assets at end of period (000's)	$	1,406,504		$	1,422,580		$	1,399,135		$	1,221,931		$	618,727		$	286,422

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Class C Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	26.58		$	25.18		$	21.75		$	15.12		$	17.66		$	17.17
Income from Investment Operations
Net investment loss (a)		(0.08	)		(0.13	)		(0.22	)		(0.18	)		(0.17	)		(0.17	)
Net realized and unrealized gain (loss)		1.47			3.09			4.56			6.83			(2.37	)		1.01
Total from Investment Operations		1.39			2.96			4.34			6.65			(2.54	)		0.84
Less Distributions Declared to Shareholders
From net realized gains		(0.31	)		(1.56	)		(0.91	)		(0.02	)		—			(0.35	)
Total Distributions Declared to Shareholders		(0.31	)		(1.56	)		(0.91	)		(0.02	)		—			(0.35	)
Net Asset Value, End of Period	$	27.66		$	26.58		$	25.18		$	21.75		$	15.12		$	17.66
Total Return (b)		5.25	%(c)(d)		11.90	%(c)		20.11	%(c)		43.99	%		(14.38	)%		4.86	%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)		1.80	%(f)		1.82	%		1.95	%		1.98	%		2.07	%		2.07	%
Net investment loss (e)		(0.54	)%(f)		(0.51	)%		(0.96	)%		(1.01	)%		(1.10	)%		(0.98	)%
Waiver/reimbursement		0.01	%(f)		0.02	%		0.02	%		—			—			—
Portfolio turnover rate		11	%(d)		16	%		20	%		10	%		13	%		20	%
Net assets at end of period (000's)	$	1,300,779		$	1,220,339		$	1,083,006		$	900,016		$	376,024		$	150,727

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

See accompanying notes to financial statements.

1-800-922-6769

Columbia Acorn International

Class A Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	33.20		$	28.75		$	22.45		$	15.32		$	18.35		$	23.84
Income from Investment Operations
Net investment income (a)		0.25			0.22			0.14			0.10			0.05			0.01
Net realized and unrealized gain (loss)		4.43			5.84			6.31			7.08			(3.07	)		(5.11	)
Total from Investment Operations		4.68			6.06			6.45			7.18			(3.02	)		(5.10	)
Less Distributions Declared to Shareholders
From net investment income		—			(0.53	)		(0.15	)		(0.05	)		(0.01	)		—
From net realized gains		(0.55	)		(1.08	)		—			—			—			(0.39	)
Total Distributions Declared to Shareholders		(0.55	)		(1.61	)		(0.15	)		(0.05	)		(0.01	)		(0.39	)
Net Asset Value, End of Period	$	37.33		$	33.20		$	28.75		$	22.45		$	15.32		$	18.35
Total Return (b)		14.11	%(c)(d)		21.42	%(c)		28.91	%(c)		46.94	%		(16.46	)%		(21.59	)%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)		1.22	%(f)		1.30	%		1.48	%		1.59	%		1.56	%		1.65	%
Net investment income (e)		1.35	%(f)		0.72	%		0.61	%		0.57	%		0.30	%		0.03	%
Waiver/reimbursement		0.01	%(f)		0.02	%		0.02	%		—			—			—
Portfolio turnover rate		19	%(d)		27	%		40	%		40	%		52	%		45	%
Net assets at end of period (000's)	$	211,021		$	142,204		$	70,582		$	52,872		$	33,806		$	25,587

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Class B Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	32.71		$	28.18		$	22.07		$	15.11		$	18.22		$	23.81
Income from Investment Operations
Net investment income (loss) (a)		0.10			0.02			(0.04	)		(0.02	)		(0.06	)		(0.12	)
Net realized and unrealized gain (loss)		4.39			5.73			6.19			6.98			(3.05	)		(5.08	)
Total from Investment Operations		4.49			5.75			6.15			6.96			(3.11	)		(5.20	)
Less Distributions Declared to Shareholders
From net investment income		—			(0.14	)		(0.04	)		—			—			—
From net realized gains		(0.55	)		(1.08	)		—			—			—			(0.39	)
Total Distributions Declared to Shareholders		(0.55	)		(1.22	)		(0.04	)		—			—			(0.39	)
Net Asset Value, End of Period	$	36.65		$	32.71		$	28.18		$	22.07		$	15.11		$	18.22
Total Return (b)		13.74	%(c)(d)		20.57	%(c)		27.91	%(c)		46.06	%		(17.07	)%		(22.04	)%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)		1.93	%(f)		2.01	%		2.27	%		2.24	%		2.21	%		2.30	%
Net investment income (loss) (e)		0.53	%(f)		0.08	%		(0.18	)%		(0.10	)%		(0.35	)%		(0.62	)%
Waiver/reimbursement		0.01	%(f)		0.02	%		0.02	%		—			—			—
Portfolio turnover rate		19	%(d)		27	%		40	%		40	%		52	%		45	%
Net assets at end of period (000's)	$	82,345		$	73,572		$	54,752		$	39,800		$	22,560		$	17,235

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Class C Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	32.68		$	28.19		$	22.06		$	15.11		$	18.21		$	23.81
Income from Investment Operations
Net investment loss (a)		0.11			(0.00	)(b)		(0.03	)		(0.01	)		(0.06	)		(0.13	)
Net realized and unrealized gain (loss)		4.37			5.71			6.20			6.96			(3.04	)		(5.08	)
Total from Investment Operations		4.48			5.71			6.17			6.95			(3.10	)		(5.21	)
Less Distributions Declared to Shareholders
From net investment income		—			(0.14	)		(0.04	)		—			—			—
From net realized gains		(0.55	)		(1.08	)		—			—			—			(0.39	)
Total Distributions Declared to Shareholders		(0.55	)		(1.22	)		(0.04	)		—			—			(0.39	)
Net Asset Value, End of Period	$	36.61		$	32.68		$	28.19		$	22.06		$	15.11		$	18.21
Total Return (c)		13.72	%(d)(e)		20.45	%(d)		28.01	%(d)		46.00	%		(17.02	)%		(22.08	)%
Ratios to Average Net Assets/Supplemental Data
Expenses (f)		2.00	%(g)		2.09	%		2.24	%		2.24	%		2.21	%		2.30	%
Net investment income (loss) (f)		0.60	%(g)		(0.01	)%		(0.15	)%		(0.06	)%		(0.35	)%		(0.62	)%
Waiver/reimbursement		0.01	%(g)		0.02	%		0.02	%		—			—			—
Portfolio turnover rate		19	%(e)		27	%		40	%		40	%		52	%		45	%
Net assets at end of period (000's)	$	76,524		$	47,325		$	30,547		$	22,990		$	14,575		$	14,327

(a) Per share data was calculated using average shares outstanding during the period.

(b) Rounds to less than $(0.01) per share.

(c) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(d) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(e) Not annualized.

(f) The benefits derived from custody fees paid indirectly had no impact.

(g) Annualized.

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

>Financial Highlights, continued

Columbia Acorn USA

Class A Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	26.52		$	24.77		$	20.74		$	14.18		$	17.50		$	14.88
Income from Investment Operations
Net investment loss (a)		(0.05	)		(0.01	)		(0.24	)		(0.22	)		(0.19	)		(0.19	)
Net realized and unrealized gain (loss)		0.59			3.13			4.41			6.78			(3.13	)		2.96
Total from Investment Operations		0.54			3.12			4.17			6.56			(3.32	)		2.77
Less Distributions Declared to Shareholders
From net realized gains		(0.10	)		(1.37	)		(0.14	)		—			—			(0.15	)
Total Distributions Declared to Shareholders		(0.10	)		(1.37	)		(0.14	)		—			—			(0.15	)
Net Asset Value, End of Period	$	26.96		$	26.52		$	24.77		$	20.74		$	14.18		$	17.50
Total Return (b)		2.04	%(c)(d)		12.68	%(c)		20.12	%(c)		46.26	%		(18.97	)%		18.65	%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)		1.25	%(f)		1.31	%		1.51	%		1.65	%		1.74	%		1.84	%
Net investment loss (e)		(0.33	)%(f)		(0.02	)%		(1.08	)%		(1.26	)%		(1.21	)%		(1.13	)%
Waiver/reimbursement		0.01	%(f)		0.01	%		0.02	%		—			—			—
Portfolio turnover rate		5	%(d)		13	%		18	%		7	%		31	%		24	%
Net assets at end of period (000's)	$	220,043		$	168,922		$	112,509		$	89,650		$	32,422		$	20,455

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Class B Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	25.61		$	24.14		$	20.36		$	14.01		$	17.40		$	14.87
Income from Investment Operations
Net investment loss (a)		(0.14	)		(0.18	)		(0.39	)		(0.32	)		(0.29	)		(0.30	)
Net realized and unrealized gain (loss)		0.58			3.02			4.31			6.67			(3.10	)		2.96
Total from Investment Operations		0.44			2.84			3.92			6.35			(3.39	)		2.66
Less Distributions Declared to Shareholders
From net realized gains		(0.10	)		(1.37	)		(0.14	)		—			—			(0.13	)
Total Distributions Declared to Shareholders		(0.10	)		(1.37	)		(0.14	)		—			—			(0.13	)
Net Asset Value, End of Period	$	25.95		$	25.61		$	24.14		$	20.36		$	14.01		$	17.40
Total Return (b)		1.73	%(c)(d)		11.84	%(c)		19.26	%(c)		45.32	%		(19.48	)%		17.92	%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)		1.96	%(f)		2.00	%		2.23	%		2.30	%		2.39	%		2.49	%
Net investment loss (e)		(1.04	)%(f)		(0.72	)%		(1.80	)%		(1.91	)%		(1.86	)%		(1.78	)%
Waiver/reimbursement		0.01	%(f)		0.01	%		0.02	%		—			—			—
Portfolio turnover rate		5	%(d)		13	%		18	%		7	%		31	%		24	%
Net assets at end of period (000's)	$	67,649		$	73,168		$	72,643		$	66,175		$	37,478		$	27,722

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Class C Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	25.59		$	24.14		$	20.36		$	14.01		$	17.40		$	14.87
Income from Investment Operations
Net investment loss (a)		(0.15	)		(0.20	)		(0.39	)		(0.32	)		(0.29	)		(0.30	)
Net realized and unrealized gain (loss)		0.58			3.02			4.31			6.67			(3.10	)		2.96
Total from Investment Operations		0.43			2.82			3.92			6.35			(3.39	)		2.66
Less Distributions Declared to Shareholders
From net realized gains		(0.10	)		(1.37	)		(0.14	)		—			—			(0.13	)
Total Distributions Declared to Shareholders		(0.10	)		(1.37	)		(0.14	)		—			—			(0.13	)
Net Asset Value, End of Period	$	25.92		$	25.59		$	24.14		$	20.36		$	14.01		$	17.40
Total Return (b)		1.69	%(c)(d)		11.76	%(c)		19.26	%(c)		45.32	%		(19.48	)%		17.92	%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)		2.05	%(f)		2.10	%		2.23	%		2.30	%		2.39	%		2.49	%
Net investment loss (e)		(1.13	)%(f)		(0.81	)%		(1.80	)%		(1.91	)%		(1.86	)%		(1.78	)%
Waiver/reimbursement		0.01	%(f)		0.01	%		0.02	%		—			—			—
Portfolio turnover rate		5	%(d)		13	%		18	%		7	%		31	%		24	%
Net assets at end of period (000's)	$	50,799		$	42,844		$	39,643		$	35,662		$	18,313		$	13,049

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

See accompanying notes to financial statements.

1-800-922-6769

Columbia Acorn International Select

Class A Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	20.36		$	17.85		$	14.45		$	10.24		$	12.07		$	17.15
Income from Investment Operations
Net investment income (loss) (a)		0.08			0.06			(0.00	)(b)		0.03			(0.01	)		(0.09	)
Net realized and unrealized gain (loss)		2.51			2.69			3.43			4.18			(1.82	)		(4.90	)
Total from Investment Operations		2.59			2.75			3.43			4.21			(1.83	)		(4.99	)
Less Distributions Declared to Shareholders
From net investment income		(0.00	)(b)		(0.24	)		(0.03	)		—			—			(0.01	)
From net realized gains		—			—			—			—			—			(0.08	)
Total Distributions Declared to Shareholders		—			(0.24	)		(0.03	)		—			—			(0.09	)
Net Asset Value, End of Period	$	22.95		$	20.36		$	17.85		$	14.45		$	10.24		$	12.07
Total Return (c)(d)		12.74	%(e)		15.60	%		23.76	%		41.11	%		(15.16	)%		(29.17	)%
Ratios to Average Net Assets/Supplemental Data
Expenses (f)		1.60	%(g)		1.70	%		1.75	%		1.80	%		1.80	%		1.80	%
Net investment income (loss) (f)		0.68	%(g)		0.34	%		(0.03	)%		0.24	%		(0.09	)%		(0.67	)%
Waiver/reimbursement		0.01	%(g)		0.10	%		0.37	%		0.44	%		0.33	%		0.23	%
Portfolio turnover rate		30	%(e)		39	%		73	%		69	%		102	%		82	%
Net assets at end of period (000's)	$	14,167		$	10,219		$	4,357		$	2,557		$	2,612		$	2,861

(a) Per share data was calculated using average shares outstanding during the period.

(b) Rounds to less than $(0.01) per share.

(c) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(d) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(e) Not annualized.

(f) The benefits derived from custody fees paid indirectly had no impact.

(g) Annualized.

Class B Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	19.80		$	17.36		$	14.12		$	10.08		$	11.96		$	17.13
Income from Investment Operations
Net investment loss (a)		(0.01	)		(0.03	)		(0.10	)		(0.06	)		(0.08	)		(0.18	)
Net realized and unrealized gain (loss)		2.45			2.61			3.34			4.10			(1.80	)		(4.90	)
Total from Investment Operations		2.44			2.58			3.24			4.04			(1.88	)		(5.08	)
Less Distributions Declared to Shareholders
From net investment income		—			(0.14	)		—			—			—			(0.01	)
From net realized gains		—			—			—			—			—			(0.08	)
Total Distributions Declared to Shareholders		—			(0.14	)		—			—			—			(0.09	)
Net Asset Value, End of Period	$	22.24		$	19.80		$	17.36		$	14.12		$	10.08		$	11.96
Total Return (b)(c)		12.32	%(d)		14.97	%		22.95	%		40.08	%		(15.72	)%		(29.73	)%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)		2.29	%(f)		2.30	%		2.38	%		2.45	%		2.45	%		2.45	%
Net investment loss (e)		(0.05	)%(f)		(0.16	)%		(0.66	)%		(0.52	)%		(0.74	)%		(1.32	)%
Waiver/reimbursement		0.07	%(f)		0.28	%		0.58	%		0.44	%		0.33	%		0.23	%
Portfolio turnover rate		30	%(d)		39	%		73	%		69	%		102	%		82	%
Net assets at end of period (000's)	$	7,910		$	6,594		$	5,097		$	3,162		$	1,835		$	2,069

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Class C Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	19.80		$	17.38		$	14.14		$	10.09		$	11.97		$	17.14
Income from Investment Operations
Net investment loss (a)		(0.02	)		(0.05	)		(0.11	)		(0.05	)		(0.08	)		(0.18	)
Net realized and unrealized gain (loss)		2.45			2.60			3.35			4.10			(1.80	)		(4.90	)
Total from Investment Operations		2.43			2.55			3.24			4.05			(1.88	)		(5.08	)
Less Distributions Declared to Shareholders
From net investment income		—			(0.13	)		—			—			—			(0.01	)
From net realized gains		—			—			—			—			—			(0.08	)
Total Distributions Declared to Shareholders		—			(0.13	)		—			—			—			(0.09	)
Net Asset Value, End of Period	$	22.23		$	19.80		$	17.38		$	14.14		$	10.09		$	11.97
Total Return (b)(c)		12.27	%(d)		14.77	%		22.91	%		40.14	%		(15.71	)%		(29.71	)%
Ratios to Average Net Assets/Supplemental Data
Expenses (e)		2.40	%(f)		2.45	%		2.45	%		2.45	%		2.45	%		2.45	%
Net investment loss (e)		(0.15	)%(f)		(0.30	)%		(0.73	)%		(0.41	)%		(0.74	)%		(1.32	)%
Waiver/reimbursement		0.01	%(f)		0.17	%		0.35	%		0.44	%		0.33	%		0.23	%
Portfolio turnover rate		30	%(d)		39	%		73	%		69	%		102	%		82	%
Net assets at end of period (000's)	$	5,006		$	4,083		$	2,543		$	3,691		$	2,915		$	3,885

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

See accompanying notes to financial statements.

Columbia Acorn Family of Funds

>Financial Highlights, continued

Columbia Acorn Select

Class A Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	22.47		$	20.83		$	18.01		$	13.93		$	15.17		$	14.12
Income from Investment Operations
Net investment loss (a)		(0.06	)		(0.09	)		(0.16	)		(0.20	)		(0.16	)		(0.10	)
Net realized and unrealized gain (loss)		1.25			2.32			3.42			4.37			(1.08	)		1.18
Total from Investment Operations		1.19			2.23			3.26			4.17			(1.24	)		1.08
Less Distributions Declared to Shareholders
From net investment income		(0.02	)		—			—			—			—			—
From net realized gains		(0.09	)		(0.59	)		(0.44	)		(0.09	)		—			(0.03	)
Total Distributions Declared to Shareholders		(0.11	)		(0.59	)		(0.44	)		(0.09	)		—			(0.03	)
Net Asset Value, End of Period	$	23.55		$	22.47		$	20.83		$	18.01		$	13.93		$	15.17
Total Return (b)		5.30	%(c)(d)		10.78	%(c)		18.16	%(c)		29.95	%		(8.17	)%(c)		7.65	%(c)
Ratios to Average Net Assets/Supplemental Data
Expenses		1.23	%(e)(f)		1.26	%(e)		1.47	%(e)		1.63	%(e)		1.70	%(e)		1.70	%
Net investment loss		(0.49	)%(e)(f)		(0.42	)%(e)		(0.86	)%(e)		(1.15	)%(e)		(1.11	)%(e)		(0.79	)%
Waiver/reimbursement		0.02	%(f)		0.03	%		0.02	%		—			0.10	%		0.18	%
Portfolio turnover rate		13	%(d)		19	%		34	%		16	%		40	%		82	%
Net assets at end of period (000's)	$	788,153		$	744,178		$	515,842		$	264,679		$	31,742		$	11,900

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Class B Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	21.71		$	20.23		$	17.64		$	13.73		$	15.05		$	14.10
Income from Investment Operations
Net investment loss (a)		(0.14	)		(0.23	)		(0.31	)		(0.29	)		(0.25	)		(0.20	)
Net realized and unrealized gain (loss)		1.21			2.24			3.34			4.29			(1.07	)		1.18
Total from Investment Operations		1.07			2.01			3.03			4.00			(1.32	)		0.98
Less Distributions Declared to Shareholders
From net realized gains		(0.09	)		(0.53	)		(0.44	)		(0.09	)		—			(0.03	)
Total Distributions Declared to Shareholders		(0.09	)		(0.53	)		(0.44	)		(0.09	)		—			(0.03	)
Net Asset Value, End of Period	$	22.69		$	21.71		$	20.23		$	17.64		$	13.73		$	15.05
Total Return (b)		4.91	%(c)(d)		10.01	%(c)		17.24	%(c)		29.14	%		(8.77	)%(c)		6.95	%(c)
Ratios to Average Net Assets/Supplemental Data
Expenses		1.95	%(e)(f)		1.99	%(e)		2.26	%(e)		2.28	%(e)		2.35	%(e)		2.35	%
Net investment loss		(1.21	)%(e)(f)		(1.15	)%(e)		(1.65	)%(e)		(1.80	)%(e)		(1.76	)%(e)		(1.44	)%
Waiver/reimbursement		0.02	%(f)		0.03	%		0.02	%		—			0.10	%		0.18	%
Portfolio turnover rate		13	%(d)		19	%		34	%		16	%		40	%		82	%
Net assets at end of period (000's)	$	203,596		$	206,441		$	185,545		$	118,064		$	33,106		$	13,358

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

Class C Shares	(Unaudited) Six months ended June 30,			Year ended December 31,
_{Selected data for a share outstanding throughout each period}	2006			2005			2004			2003			2002			2001
Net Asset Value, Beginning of Period	$	21.69		$	20.23		$	17.64		$	13.73		$	15.05		$	14.10
Income from Investment Operations
Net investment loss (a)		(0.15	)		(0.25	)		(0.30	)		(0.30	)		(0.25	)		(0.20	)
Net realized and unrealized gain (loss)		1.21			2.24			3.33			4.30			(1.07	)		1.18
Total from Investment Operations		1.06			1.99			3.03			4.00			(1.32	)		0.98
Less Distributions Declared to Shareholders
From net realized gains		(0.09	)		(0.53	)		(0.44	)		(0.09	)		—			(0.03	)
Total Distributions Declared to Shareholders		(0.09	)		(0.53	)		(0.44	)		(0.09	)		—			(0.03	)
Net Asset Value, End of Period	$	22.66		$	21.69		$	20.23		$	17.64		$	13.73		$	15.05
Total Return (b)		4.87	%(c)(d)		9.91	%(c)		17.24	%(c)		29.14	%		(8.77	)%(c)		6.95	%(c)
Ratios to Average Net Assets/Supplemental Data
Expenses		2.04	%(e)(f)		2.08	%(e)		2.25	%(e)		2.28	%(e)		2.35	%(e)		2.35	%
Net investment loss		(1.30	)%(e)(f)		(1.24	)%(e)		(1.64	)%(e)		(1.80	)%(e)		(1.76	)%(e)		(1.44	)%
Waiver/reimbursement		0.02	%(f)		0.03	%		0.02	%		—			0.10	%		0.18	%
Portfolio turnover rate		13	%(d)		19	%		34	%		16	%		40	%		82	%
Net assets at end of period (000's)	$	155,134		$	149,160		$	110,435		$	64,212		$	10,919		$	4,945

(a) Per share data was calculated using average shares outstanding during the period.

(b) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(c) Had the Investment Adviser and/or Transfer Agent not waived and/or reimbursed a portion of expenses, total return would have been reduced.

(d) Not annualized.

(e) The benefits derived from custody fees paid indirectly had no impact.

(f) Annualized.

See accompanying notes to financial statements.

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Columbia Acorn Family of Funds

>Notes to Financial Statements (Unaudited)

1. Nature of Operations

Class B shares are subject to a CDSC if sold within six years of purchase. Class B shares will convert to Class A shares automatically eight years after purchase.

Class C shares are subject to a CDSC on redemptions made within one year after purchase.

The financial highlights for Class Z shares are presented in a separate semiannual report. The semiannual financial statements for Columbia Thermostat Fund, another Fund of the Trust, begins on page 80 of this report.

2. Significant Accounting Policies

>Security valuation

Securities of the Funds are valued at marked value or, if a market quotation for a security is not readily available or is deemed not to be reliable because of events or circumstances that have occurred between the market quotation and the time as of which the security is to be valued, the security is valued at a fair value determined in accordance with procedures established by the Board of Trustees. Securities traded on securities exchanges or in over-the-counter markets in which transaction prices are reported are valued at the last sales price at the time of valuation. If a security is traded principally on the Nasdaq Stock Market Inc., the Nasdaq Official Closing Price will be applied. Securities for which there are no reported sales on the valuation date are valued at the latest bid quotation. Short-term debt obligations having a maturity of 60 days or less from the valuation date are valued on an amortized cost basis, which approximate fair value. Securities for which quotations are not available are valued at a fair value as determined in good faith by the Board of Trustees. The Trust has retained an independent statistical fair value pricing service to assist in the fair valuation process for securities principally traded in a foreign market in order to adjust for possible changes in value that may occur between the close of the foreign exchange and the time at which Fund shares are priced. If a security is valued at a "fair value," that value may be different from the last quoted market price for the security.

>Repurchase agreements

Columbia Acorn Family of Funds

>Notes to Financial Statements (Unaudited), continued

>Foreign currency translations

>Security transactions and investment income

Awards from class action litigation may be recorded as a reduction of cost. If the Funds no longer own the applicable securities, the proceeds are recorded as realized gains.

>Restricted Securities

>Use of estimates

>Financial instruments

None of the Funds entered into futures contracts or forward foreign currency contracts during the six months ended June 30, 2006.

>Fund share valuation

>Custody fees/credits

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as a reduction of total expenses in the Statements of Operations.

>Federal income taxes

>Foreign capital gains taxes

>Distributions to Shareholders

Distributions to shareholders are recorded on the ex-date.

>Indemnification

3. Federal Tax Information

The tax character of distributions paid during the years ended December 31, 2005 was as follows:

	Ordinary Income*		Long-Term Capital Gains
(in thousands)
Columbia Acorn Fund	$	89,415	$	846,121
Columbia Acorn International		54,197		89,135
Columbia Acorn USA		1,825		56,868
Columbia Acorn International Select		1,037		—
Columbia Acorn Select		7,041		39,716

*For tax purposes short-term capital gains distributions, if any, are considered ordinary income distributions.

The following capital loss carryforwards, determined as of December 31, 2005, may be available to reduce taxable income arising from future net realized gains on investments, if any, to the extent permitted by the Internal Revenue Code:

Year of Expiration		Columbia Acorn USA			Columbia Acorn International Select
(in thousands)
	2009	$	2,023	*	$	10,593
	2010		506			12,528
	2011		—			2,488
	TOTAL	$	2,529		$	25,609

The following capital loss carryforwards were utilized during the year ended December 31, 2005.

(In thousands)
Columbia Acorn International	$	62,579
Columbia Acorn USA		7,025
Columbia Acorn International Select		5,542

4. Transactions with Affiliates

Columbia WAM furnishes continuing investment supervision to the Funds and is responsible for the overall management of the Funds' business affairs.

Effective August 1, 2006, under the Funds' investment management agreement, fees are accrued daily and paid monthly to Columbia WAM at the annual rates shown in the

Columbia Acorn Family of Funds

>Notes to Financial Statements (Unaudited), continued

table below for Columbia Acorn USA and Columbia Acorn Select:

Columbia Acorn USA
Assets	Rate of Fee
Up to $200 million		0.940	%
$200 million to $500 million		0.890	%
$500 million to $2 billion		0.840	%
$2 billion to $3 billion		0.800	%
$3 billion and over		0.700	%
Columbia Acorn Select
Assets	Rate of Fee
Up to $700 million		0.850	%
$700 million to $2 billion		0.800	%
$2 billion to $3 billion		0.750	%
$3 billion and over		0.700	%

For the period covered by this report as provided under the Funds' investment management agreement, fees were

accrued daily and paid monthly to Columbia WAM at the annual rates shown in the table below for each Fund.

Columbia Acorn Fund
Assets	Rate of Fee
Up to $700 million		0.740	%
$700 million to $2 billion		0.690	%
$2 billion to $6 billion		0.640	%
$6 billion and over		0.630	%
Columbia Acorn International
Assets	Rate of Fee
Up to $100 million		1.190	%
$100 million to $500 million		0.940	%
$500 million and over		0.740	%
Columbia Acorn USA
Assets	Rate of Fee
Up to $200 million		0.940	%
$200 million to $500 million		0.890	%
$500 million and over		0.840	%
Columbia Acorn Select
Assets	Rate of Fee
Up to $700 million		0.850	%
$700 million and over		0.800	%
Columbia Acorn International Select
All Assets		0.940	%

For the six months ended June 30, 2006, the Funds' effective investment advisory fee rates were as follows:

Columbia Acorn Fund	0.64	%
Columbia Acorn International	0.78	%
Columbia Acorn USA	0.87	%
Columbia Acorn International Select	0.94	%
Columbia Acorn Select	0.82	%

>Expense Limit

Columbia WAM has voluntarily agreed to reimburse the ordinary operating expenses (exclusive of 12b-1 service and distribution fees, interest, taxes and extraordinary expenses, if any) exceeding 1.45% of the average annual net assets for Columbia Acorn International Select Class A, Class B and Class C shares and 1.35% of the average annual net assets for Columbia Acorn Select Class A, Class B and Class C shares. This arrangement may be modified or terminated by either the Funds or Columbia WAM on 30 days notice.

Expenses reimbursed by Columbia WAM for Columbia Acorn International Select for the six months ended June 30, 2006 were $2,157.

Columbia WAM provides administrative services and receives an administration fee from the Funds at the following rates:

Columbia Acorn Trust
Average daily net asset value:
On the first $8 billion	0.05	%
Next $8 billion	0.04	%
Average daily net asset in excess of $16 billion	0.03	%

For the six months ended June 30, 2006 each Fund's effective administration fee rate was 0.041%. Columbia WAM has delegated to Columbia Management Advisors, LLC, an indirect, wholly owned subsidiary of BOA, responsibility to provide certain administrative services to the Funds.

Columbia Management Distributors, Inc. ("CMDI"), a wholly owned subsidiary of BOA, is the Funds' principal underwriter and receives no compensation on the sale of Class Z shares.

For the six months ended June 30, 2006, Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select and Columbia Acorn Select have been advised that CMDI retained $728,745 in underwriting discounts on the sale of Class A shares and received CDSCs of 1,264,118 and $57,929, on Class B and Class C share redemptions, respectively.

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Each Fund has adopted a 12b-1 plan which requires it to pay CMDI a monthly service fee equal to 0.25% annually of the average daily net assets attributable to Class A, Class B and Class C shares. The 12b-1 plan also requires each fund to pay CMDI a monthly distribution fee equal to 0.60% and 0.75%, annually, of the average daily net assets attributable to Class B and Class C shares, respectively. Effective August 1, 2006 the monthly distribution fee rate for Class B shares was reduced to 0.50% annually, of the average daily net assets. For the period covered by this report the monthly distribution fee was 0.60% for Class B shares.

Expenses waived by the Transfer Agent for the six months ended June 30, 2006 were as follows:

(in thousands)
Columbia Acorn Fund	$	817
Columbia Acorn International		96
Columbia Acorn USA		48
Columbia Acorn International Select		7
Columbia Acorn Select		170

(in thousands)
Columbia Acorn Fund	$	303
Columbia Acorn International		47
Columbia Acorn USA		21
Columbia Acorn International Select		1
Columbia Acorn Select		15

	Purchases		Sales
(in thousands)
Columbia Acorn Fund	$	306	$	9,383
Columbia Acorn International		19,613		1,299
Columbia Acorn International Select		44		—
Columbia Acorn Select		—		97

5. Borrowing Arrangements

Columbia Acorn Family of Funds

>Notes to Financial Statements (Unaudited), continued

6. Investment Transactions

The aggregate cost of purchases and proceeds from sales other than short-term obligations for the six months ended June 30, 2006 were:

Columbia Acorn Fund
(in thousands)
Investment securities
Purchases	$	2,536,172
Proceeds from sales		1,828,147
Columbia Acorn International
(in thousands)
Investment securities
Purchases	$	872,256
Proceeds from sales		618,788
Columbia Acorn USA
(in thousands)
Investment securities
Purchases	$	298,839
Proceeds from sales		66,493
Columbia Acorn International Select
(in thousands)
Investment securities
Purchases	$	40,440
Proceeds from sales		31,655
Columbia Acorn Select
(in thousands)
Investment securities
Purchases	$	273,545
Proceeds from sales		235,105

7. Redemption Fees

For the six months ended June 30, 2006, the redemption fees for the Class Z shares of Columbia Acorn International and Columbia Acorn International Select amounted to $107 and $4, respectively, and are accounted for as additions to paid in capital.

8. Other

9. Legal Proceedings

The Trust and Columbia WAM are also defendants in a class action lawsuit that alleges, in summary, that the Trust and Columbia WAM exposed shareholders of Columbia Acorn International to trading by market timers by allegedly: (a) failing to properly evaluate daily whether a significant event affecting the value of the Fund's securities had occurred after foreign markets had closed but before the calculation of the Fund's net asset value ("NAV"); (b) failing to implement the Fund's portfolio valuation and share pricing policies and procedures; and (c) failing to know and implement applicable rules and regulations concerning the calculation of NAV. The Seventh Circuit ruled that the plaintiffs' state law claims were preempted under federal law resulting in the dismissal of plaintiffs' complaint. Plaintiffs appealed the Seventh Circuit's ruling to the United States Supreme Court.

1-800-922-6769

The Trust and Columbia WAM intend to defend these suits vigorously.

For the six months ended June 30, 2006, Columbia Management has assumed consulting services and legal fees incurred by the Funds in connection with these matters and the amounts are as follows:

(in thousands)
Columbia Acorn Fund	$	84
Columbia Acorn International		16
Columbia Acorn USA		7
Columbia Acorn International Select		1
Columbia Acorn Select		9

Columbia Thermostat Fund

>Statement of Investments (Unaudited), June 30, 2006

Number of Shares or Principal Amount (000)			Value (000)
		>Stock Funds: 50.9%
	1,828,532	Columbia Large Cap Enhanced Core Fund, Class Z	$	24,210
	1,542,750	Columbia Dividend Income Fund, Class Z		19,300
	394,773	Columbia Acorn International, Class Z		14,836
	498,693	Columbia Acorn Fund, Class Z		14,706
	1,035,323	Columbia Large Cap Value Fund, Class Z		14,536
	409,815	Columbia Acorn Select, Class Z		9,782
		Total Stock Funds (Cost: $90,716)		97,370
		>Bond Funds: 49.1%
	5,468,354	Columbia Intermediate Bond Fund, Class Z		47,083
	2,774,361	Columbia Federal Securities Fund, Class Z		28,187
	2,289,736	Columbia Conservative High Yield Fund, Class Z		18,730
		Total Bond Funds (Cost: $97,372)		94,000
Short-Term Obligation: 0.4%
$	685	Repurchase Agreement with State Street Bank & Trust dated 6/30/06, due 7/03/06 at 4.93% collateralized by Federal Home Loan Bank, maturing 12/12/08 market value $710 (repurchase proceeds: $685)		685
		(Cost: $685)		685
	Total Investments: 100.4% (Cost: $188,773)(a)			192,055
	Cash and Other Assets Less Liabilities: (0.4)%			(709	)
	Total Net Assets: 100%		$	191,346

>Notes to Statement of Investments (in thousands)

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Columbia Thermostat Fund

>Statement of Assets and Liabilities (Unaudited)

June 30, 2006

(in thousands)
Assets:
Unaffiliated investments, at value (cost: $685)	$	685
Affiliated investments, at value (cost: $188,088)		191,370
Cash		—	*
Receivable for: Fund shares sold		79
Dividends and interest		445
Expense reimbursement due from Investment Adviser		29
Total Assets		192,608
Liabilities:
Payable for:
Investments purchased		445
Fund shares redeemed		604
Management fee		16
Administration fee		7
Transfer agent fees		24
Trustees' fees		2
Custody fees		2
Reports to shareholders		57
12b-1 Service & Distribution fees		93
Deferred Trustees' fees		6
Other liabilities		6
Total Liabilities		1,262
Net Assets	$	191,346
Composition of Net Assets:
Paid in capital	$	180,294
Undistributed net investment income		3,327
Accumulated net realized gain		4,443
Net unrealized appreciation on investments		3,282
Net Assets	$	191,346
Net asset value per share – Class A (a)	$	12.53
(Net assets/shares)		($63,627/5,076)
Maximum offering price per share – Class A (b)	$	13.29
(Net asset value per share/front-end sales charge)		($12.53/0.9425)
Net asset value and offering price per share – Class B (a)	$	12.53
(Net assets/shares)		($73,634/5,876)
Net asset value and offering price per share – Class C (a)	$	12.52
(Net assets/shares)		($27,319/2,182)
Net asset value, offering and redemption price per share – Class Z	$	12.53
(Net assets/shares)		($26,766/2,136)

*Rounds to less than $500.

(a) Redemption price per share is equal to net asset value less any applicable contingent deferred sales charge.

(b) On sales of $50,000 or more the offering price is reduced.

See accompanying notes to financial statements.

Columbia Thermostat Fund

>Statement of Operations (Unaudited)
For the Six Months Ended June 30, 2006

(in thousands)
Investment Income:
Dividends from affiliated investment company shares	$	4,130
Interest income		17
Total Investment Income		4,147
Expenses:
Management fee		99
Administration fee		40
12b-1 Service and Distribution fees:
Class A		85
Class B		324
Class C		138
Transfer agent fees:
Class A		51
Class B		71
Class C		25
Class Z		13
Trustees' fees		2
Custody fees		2
Reports to shareholders		70
Compliance fees		3
Non-recurring costs (See Note 7)		1
Other expenses		55
Total expenses		979
Less custody fees paid indirectly		—	*
Less reimbursement of expenses by Investment Adviser		(153	)
Less fees waived by Transfer Agent		(31	)
Non-recurring costs reimbursed (See Note 7)		(1	)
Net Expenses		794
Net Investment Income		3,353
Net Realized and Unrealized Gain on Investments:
Net realized gain on:
Affiliated investments		4,104
Distributions from affiliated investment company shares		880
Net realized gain		4,984
Net change in unrealized appreciation (depreciation) on affiliated investments		(3,742	)
Net realized and unrealized gain		1,242
Net Increase in Net Assets from Operations	$	4,595

*Rounds to less than $500.

See accompanying notes to financial statements.

1-800-922-6769

Columbia Thermostat Fund

>Statement of Changes in Net Assets

Increase in Net Assets:	(Unaudited) Six months ended June 30,			Year ended December 31,
(in thousands)	2006			2005
Operations:
Net investment income	$	3,353		$	5,484
Net realized gain on affiliated investments and distributions from affiliated investment company shares		4,984			14,700
Net change in net unrealized appreciation (depreciation) on affiliated investments		(3,742	)		(10,409	)
Net Increase from Operations		4,595			9,775
Distributions Declared to Shareholders From:
Net investment income – Class A		(70	)		(2,069	)
Net realized gain – Class A		(1,229	)		(4,875	)
Net investment income – Class B		—	*		(1,831	)
Net realized gain – Class B		(1,409	)		(5,382	)
Net investment income – Class C		—			(617	)
Net realized gain – Class C		(520	)		(1,972	)
Net investment income – Class Z		(98	)		(797	)
Net realized gain – Class Z		(504	)		(1,697	)
Total Distributions to Shareholders		(3,830	)		(19,240	)
Share Transactions:
Subscriptions – Class A		4,262			15,104
Distributions reinvested – Class A		1,185			6,273
Redemptions – Class A		(13,279	)		(24,089	)
Net Decrease – Class A		(7,832	)		(2,712	)
Subscriptions – Class B		2,467			8,919
Distributions reinvested – Class B		1,280			6,512
Redemptions – Class B		(8,800	)		(11,391	)
Net Increase (Decrease) – Class B		(5,053	)		4,040
Subscriptions – Class C		2,960			5,664
Distributions reinvested – Class C		460			2,303
Redemptions – Class C		(4,467	)		(9,480	)
Net Decrease – Class C		(1,047	)		(1,513	)
Subscriptions – Class Z		2,323			5,843
Distributions reinvested – Class Z		578			2,384
Redemptions – Class Z		(1,744	)		(2,485	)
Net Increase – Class Z		1,157			5,742
Net Increase (Decrease) from Share Transactions		(12,775	)		5,557
Total Decrease in Net Assets		(12,010	)		(3,908	)
Net Assets:
Beginning of period		203,356			207,264
End of period	$	191,346		$	203,356
Undistributed Net Investment Income	$	3,327		$	142

*Rounds to less than $500.

See accompanying notes to financial statements.

Columbia Thermostat Fund

>Statement of Changes in Net Assets, continued

Changes in Shares of Beneficial Interest:	(Unaudited) Six months ended June 30,			Year ended December 31,
(in thousands)	2006			2005
Subscriptions – Class A		333			1,151
Shares issued in reinvestment and capital gains – Class A		95			497
Less shares redeemed – Class A		(1,039	)		(1,840	)
Net Decrease – Class A		(611	)		(192	)
Subscriptions – Class B		193			684
Shares issued in reinvestment and capital gains – Class B		102			515
Less shares redeemed – Class B		(689	)		(870	)
Net Increase (Decrease) – Class B		(394	)		329
Subscriptions – Class C		232			434
Shares issued in reinvestment and capital gains – Class C		37			182
Less shares redeemed – Class C		(350	)		(725	)
Net Decrease – Class C		(81	)		(109	)
Subscriptions – Class Z		182			446
Shares issued in reinvestment and capital gains – Class Z		46			189
Less shares redeemed – Class Z		(136	)		(189	)
Net Increase – Class Z		92			446
Net Increase (Decrease) in Shares of Beneficial Interest		(994	)		474

See accompanying notes to financial statements.

1-800-922-6769

Columbia Thermostat Fund

>Financial Highlights

Class A Shares	(Unaudited) Six months ended June 30,			Year Ended December 31,						Inception March 3, 2003 through December 31,
Selected data for a share outstanding throughout each period	2006			2005			2004			2003
Net Asset Value, Beginning of Period	$	12.49		$	13.11		$	12.30		$	10.10
Income from Investment Operations
Net investment income (a)		0.23			0.39			0.28			0.18
Net realized and unrealized gain		0.06			0.29			0.81			2.15
Total from Investment Operations		0.29			0.68			1.09			2.33
Less Distributions Declared to Shareholders
From net investment income		(0.01	)		(0.39	)		(0.25	)		(0.13	)
From net realized gains		(0.24	)		(0.91	)		(0.03	)		(0.00	)(b)
Total Distributions Declared to Shareholders		(0.25	)		(1.30	)		(0.28	)		(0.13	)
Net Asset Value, End of Period	$	12.53		$	12.49		$	13.11		$	12.30
Total Return (c)(d)		2.37	%(e)		5.25	%		8.92	%		23.10	%(e)
Ratios to Average Net Assets/Supplemental Data
Expenses (f)(g)		0.50	%(h)		0.50	%		0.50	%		0.57	%(h)
Net investment income (g)		3.65	%(h)		2.97	%		2.23	%		1.86	%(h)
Reimbursement/waiver		0.17	%(h)		0.15	%		0.33	%		0.66	%(h)
Portfolio turnover rate		29	%(e)		96	%		67	%		61	%
Net assets at end of period (000's)	$	63,627		$	71,034		$	77,092		$	42,271

(b) Rounds to less than $(0.01) per share.

(c) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(d) Had the Investment Adviser and/or Transfer Agent not reimbursed a portion of expenses, total return would have been reduced.

(e) Not annualized.

(f) Does not include expenses of the investment companies in which the Fund invests.

(g) The benefits derived from custody fees paid indirectly had no impact.

(h) Annualized.

Class B Shares	(Unaudited) Six months ended June 30,			Year Ended December 31,						Inception March 3, 2003 through December 31,
Selected data for a share outstanding throughout each period	2006			2005			2004			2003
Net Asset Value, Beginning of Period	$	12.51		$	13.14		$	12.32		$	10.10
Income from Investment Operations
Net investment income (a)		0.20			0.31			0.19			0.10
Net realized and unrealized gain		0.06			0.28			0.83			2.16
Total from Investment Operations		0.26			0.59			1.02			2.26
Less Distributions Declared to Shareholders
From net investment income		—			(0.31	)		(0.17	)		(0.04	)
From net realized gains		(0.24	)		(0.91	)		(0.03	)		(0.00	)(b)
Total Distributions Declared to Shareholders		(0.24	)		(1.22	)		(0.20	)		(0.04	)
Net Asset Value, End of Period	$	12.53		$	12.51		$	13.14		$	12.32
Total Return (c)(d)		2.10	%(e)		4.56	%		8.27	%		22.38	%(e)
Ratios to Average Net Assets/Supplemental Data
Expenses (f)(g)		1.10	%(h)		1.10	%		1.18	%		1.32	%(h)
Net investment income (g)		3.09	%(h)		2.39	%		1.55	%		1.06	%(h)
Reimbursement/waiver		0.21	%(h)		0.19	%		0.29	%		0.66	%(h)
Portfolio turnover rate		29	%(e)		96	%		67	%		61	%
Net assets at end of period (000's)	$	73,634		$	78,444		$	78,040		$	51,501

(b) Rounds to less than $(0.01) per share.

(c) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(d) Had the Investment Adviser and/or Transfer Agent not reimbursed a portion of expenses, total return would have been reduced.

(e) Not annualized.

(f) Does not include expenses of the investment companies in which the Fund invests.

(g) The benefits derived from custody fees paid indirectly had no impact.

(h) Annualized.

Class C Shares	(Unaudited) Six months ended June 30,			Year Ended December 31,						Inception March 3, 2003 through December 31,
Selected data for a share outstanding throughout each period	2006			2005			2004			2003
Net Asset Value, Beginning of Period	$	12.51		$	13.13		$	12.32		$	10.10
Income from Investment Operations
Net investment income (a)		0.19			0.29			0.19			0.11
Net realized and unrealized gain		0.06			0.29			0.81			2.15
Total from Investment Operations		0.25			0.58			1.00			2.26
Less Distributions Declared to Shareholders
From net investment income		—			(0.29	)		(0.16	)		(0.04	)
From net realized gains		(0.24	)		(0.91	)		(0.03	)		(0.00	)(b)
Total Distributions Declared to Shareholders		(0.24	)		(1.20	)		(0.19	)		(0.04	)
Net Asset Value, End of Period	$	12.52		$	12.51		$	13.13		$	12.32
Total Return (c)(d)		2.02	%(e)		4.49	%		8.13	%		22.38	%(e)
Ratios to Average Net Assets/Supplemental Data
Expenses (f)(g)		1.25	%(h)		1.25	%		1.25	%		1.32	%(h)
Net investment income (g)		2.96	%(h)		2.21	%		1.48	%		1.10	%(h)
Reimbursement/waiver		0.21	%(h)		0.19	%		0.26	%		0.66	%(h)
Portfolio turnover rate		29	%(e)		96	%		67	%		61	%
Net assets at end of period (000's)	$	27,319		$	28,316		$	31,161		$	20,087

(b) Rounds to less than $(0.01) per share.

(c) Total return at net asset value assuming all distributions reinvested and no initial sales charge or contingent deferred sales charge.

(d) Had the Investment Adviser and/or Transfer Agent not reimbursed a portion of expenses, total return would have been reduced.

(e) Not annualized.

(f) Does not include expenses of the investment companies in which the Fund invests.

(g) The benefits derived from custody fees paid indirectly had no impact.

(h) Annualized.

See accompanying notes to financial statements.

Columbia Thermostat Fund

>Notes to Financial Statements (Unaudited)

1. Nature of Operations

Columbia Thermostat Fund (the "Fund"), is a series of Columbia Acorn Trust (the "Trust"), an open-end management investment company organized as a Massachusetts business trust. The Fund may issue an unlimited number of shares. The Fund currently offers four classes of shares: Class A, Class B, Class C and Class Z.

Class B shares are subject to a CDSC if sold within six years of purchase. Class B shares will convert to Class A shares automatically eight years after purchase.

Class C shares are subject to a CDSC on redemptions made within one year after purchase.

Class Z shares are offered continuously at net asset value. There are certain restrictions on the purchase of Class Z shares.

The investment objective of the Fund is to provide long-term total return. The Fund pursues its investment objective by investing in shares of other mutual funds. As a 'fund of funds', under normal circumstances, the Fund allocates at least 95% of its net assets among a selected group of stock and bond mutual funds (the "Portfolio Funds") according to the current level of the Standard & Poor's 500 Stock Index in relation to predetermined ranges set by the Fund's investment adviser. As of June 30, 2006, the Fund invested in six stock Portfolio Funds (Columbia Acorn Fund, Columbia Acorn Select, Columbia Large Cap Value Fund, Columbia Acorn International, Columbia Dividend Income Fund and Columbia Large Cap Enhanced Core Fund) and three bond Portfolio Funds (Columbia Federal Securities Fund, Columbia Intermediate Bond Fund and Columbia Conservative High Yield Fund). The Fund may also invest up to 5% of its net assets plus any cash received that day in cash, repurchase agreements, high quality short-term paper and government securities.

Investment income, realized and unrealized gains and losses, and certain fund-level expenses are borne pro rata on the basis of the relative net assets of all classes, except each class bears certain expenses unique to that class such as distribution services, transfer agent, and certain other class specific expenses. Differences in class expenses may result in payment of different dividend distributions for each class. All the share classes of the Trust have equal rights with respect to voting subject to class specific arrangements.

2. Significant Accounting Policies

>Security valuation

>Repurchase agreements

>Security transactions and investment income

>Use of estimates

1-800-922-6769

statements and accompanying notes. Actual results may differ from those estimates.

>Fund share valuation

Fund shares are sold and redeemed on a continuing basis at net asset value. Net asset value per share is determined daily as of the close of trading on the New York Stock Exchange (the "Exchange") on each day the Exchange is open for trading. All income, expenses (other than Class A, Class B and Class C 12b-1 service and distribution fees, and Class A, Class B, Class C and Class Z transfer agent fees) and realized and unrealized gains (losses) of the Fund are allocated to each class proportionately on a daily basis for purposes of determining the net asset value of each class.

>Custody fees/credits

>Federal income taxes

>Distributions to Shareholders

Distributions to shareholders are recorded on the ex-date.

>Indemnification

In the normal course of business, the Fund enters into contracts that contain a variety of representations and warranties and which provide general indemnities. The Fund's maximum exposure under these arrangements is unknown, as this would involve future claims against the Fund. Also, under the Trust's organizational documents, the Trustees and Officers of the Trust are indemnified against certain liabilities that may arise out of their duties to the Trust. However, based on experience, the Fund expects the risk of loss due to these warranties and indemnities to be minimal.

3. Federal Tax Information

The tax character of distributions paid during the years ended December 31, 2005 was as follows:

(in thousands)
Distributions paid from:
Ordinary Income*	$	8,262
Long-Term Capital Gains		10,978

*For tax purposes short-term capital gains distributions, if any, are considered ordinary income distributions.

In June 2006, the Financial Accounting Standards Board ("FASB") issued FASB Interpretation No. 48, Accounting for Uncertainty in Income Taxes, an Interpretation of FASB Statement 109 (the "Interpretation"). This Interpretation is effective for fiscal years beginning after December 15, 2006 and is to be applied to all tax positions upon initial adoption. This Interpretation prescribes a minimum recognition threshold and measurement method for the financial statement recognition of tax positions taken or expected to be taken in a tax return and also requires certain expanded disclosures. Columbia Wanger Asset Management, L.P. ("Columbia WAM"), a wholly owned subsidiary of Columbia Management Group, Inc., which in turn is an indirect, wholly owned subsidiary of Bank of America Corporation ("BOA"), has recently begun to evaluate the application of this Interpretation to the Fund and has not at this time quantified the impact, if any, resulting from the adoption of this Interpretation on the Fund's financial statements.

4. Transactions with Affiliates

Columbia WAM furnishes continuing investment supervision to the Fund and is responsible for the overall management of the Fund's business affairs.

Under the Fund's investment management agreement, fees are accrued daily and paid monthly to Columbia WAM at the annual rate of 0.10% of the Fund's average daily net assets.

>Expense Limit

Columbia WAM has contractually agreed to reimburse the direct operating expenses (exclusive of 12b-1 service and distribution fees, interest and fees on borrowings and expenses associated with the Fund's investment in other investment companies) exceeding 0.25% of the average annual net assets of the Fund's Class A, Class B and Class C shares annually through April 30, 2007.

Fees reimbursed amounted to $153,234 for the six months ended June 30, 2006.

Columbia Thermostat Fund

>Notes to Financial Statements (Unaudited), continued

Columbia WAM has the right to recoup expense reimbursement payments made to the Fund through December 31, 2006. No expenses were recouped through June 30, 2006.

Columbia WAM provides administrative services and receives an administration fee from the Fund at the following annual rates:

Columbia Acorn Trust
Average daily net asset value:
On the first $8 billion	0.05	%
Next $8 billion	0.04	%
Average daily net asset value in excess of $16 billion	0.03	%

Columbia Management Distributors, Inc. ("CMDI"), a wholly owned subsidiary of BOA, is the Fund's principal indirect underwriter and receives no compensation on the sale of Class Z shares.

For the six months ended June 30, 2006, the Fund has been advised that CMDI retained $16,790 in underwriting discounts on the sale of Class A shares and received CDSCs of $115,164 and $4,142, respectively, on Class B and Class C share redemptions, respectively.

The Fund has adopted a 12b-1 plan which requires it to pay CMDI a monthly service fee equal to 0.25% annually of the average daily net assets attributable to Class A, Class B and Class C shares. The 12b-1 plan also requires the Fund paid CMDI a monthly distribution fee equal to 0.60% and 0.75%, annually, of the average daily net assets attributable to Class B and Class C shares, respectively. Effective August 1, 2006 the monthly distribution fee rate for Class B shares was reduced to 0.50% annually, of the average daily net assets. For the period covered by this report the monthly distribution fee was 0.60% for Class B shares.

Columbia Management Services, Inc. (the "Transfer Agent"), a wholly owned subsidiary of BOA, provides shareholder services to the Fund and has contracted with Boston Financial Data Services ("BFDS") to serve as sub-transfer agent. For such services, the Transfer Agent receives a fee, paid monthly, at the annual rate of $21.00 per open account. The Transfer Agent also receives reimbursement for certain out-of-pocket expenses. The Transfer Agent has agreed to waive the reimbursement for certain out-of-pocket expenses for the period covered by this report. Expenses waived by the Transfer Agent for the six months ended June 30, 2006 were $30,576.

Certain officers and trustees of the Trust are also officers of Columbia WAM. The Trust makes no direct payments to its officers and trustees who are affiliated with Columbia WAM. Trustees' fees and expenses paid by the Fund for the six months ended June 30, 2006 were $2,362.

5. Borrowing Arrangements

The Trust participates in a $150 million credit facility, which was entered into to facilitate portfolio liquidity. Interest is charged to each participating fund based on its borrowings at a rate per annum equal to the Federal Funds rate plus 0.50%. In addition, a commitment fee of 0.10% per annum is accrued and apportioned among the participating funds based on their pro-rata portion of the unutilized line of credit. The commitment fee is included in "Other expenses" in the Statement of Operations. No amounts were borrowed under this facility for the six months ended June 30, 2006.

6. Investment Transactions

The aggregate cost of purchases and proceeds from sales other than short-term obligations for the six months ended June 30, 2006 were:

(in thousands)
Purchases	$	57,973
Proceeds from sales		69,846

7. Legal Proceedings

The Trust and Columbia WAM are also defendants in a class action lawsuit that alleges, in summary, that the Trust and Columbia WAM exposed shareholders of Columbia Acorn

1-800-922-6769

International to trading by market timers by allegedly: (a) failing to properly evaluate daily whether a significant event affecting the value of the Fund's securities had occurred after foreign markets had closed but before the calculation of the Fund's net asset value ("NAV"); (b) failing to implement the Fund's portfolio valuation and share pricing policies and procedures; and (c) failing to know and implement applicable rules and regulations concerning the calculation of NAV. The Seventh Circuit ruled that the plaintiffs' state law claims were preempted under federal law resulting in the dismissal of plaintiffs' complaint. Plaintiffs appealed the Seventh Circuit's ruling to the United States Supreme Court.

In addition to the rescission of sales charges, plaintiffs seek recovery of actual damages, attorneys' fees and costs. The case had been transferred to the MDL Action in the federal district court of Maryland.

On April 4, 2006, all of the parties to the MDL Action executed a letter settlement agreement intended to fully resolve all of the lawsuits consolidated in the MDL Action aswell as the Fair Valuation Lawsuit. The settlement has not yet been finalized or approved by the court.

The Trust and Columbia WAM intend to defend these suits vigorously.

For the six months ended June 30, 2006, Columbia Management has assumed $934 of consulting services and legal fees incurred by the Fund in connection with these matters.

[Excerpts from:]

Columbia Acorn Trust

Management Fee Evaluation of the Senior Officer

Prepared Pursuant to the New York Attorney General's
Assurance of Discontinuance

Robert P. Scales
Senior Vice President,
Chief Legal Officer
and General Counsel

2006

Introduction

According to the Order, the Senior Officer's evaluation must consider at least the following:

(1) Management fees (including components thereof) charged to institutional and other clients of CWAM for like services;

(2) Management fees (including any components thereof) charged by other mutual fund companies for like services;

(3) Costs to CWAM and its affiliates of supplying services pursuant to the management fee agreements, excluding any intra-corporate profit;

(4) Profit margins of CWAM and its affiliates from supplying such services;

(5) Possible economies of scale as the Acorn Funds grow larger; and

(6) The nature and quality of CWAM's services, including the performance of each Acorn Fund.

2005 Evaluation

This evaluation was performed in cooperation and regular communication with the Contract Review Committee of the Board of Trustees.

Process and Independence

The Fee Reductions Mandated under the Order

Conclusions

My review of the data and other material above leads to the following conclusions with respect to the factors identified in the Order.

b. Compliance. CWAM has a reasonably designed compliance program that protects shareholders.

c. Administrative Services. The Acorn Funds benefit from a variety of administrative services that are performed by CWAM and CMAI.

Recommendations

I believe the Trustees should:

1. Continue to consider ways to restructure the advisory fee beyond the current breakpoint schedule to reflect more fully economies of scale.

2. Monitor the performance of Acorn International and Acorn International Select.

3. Continue to monitor CWAM's capacity limitations to insure that Acorn Fund's expanding assets do not impair investment performance.

Robert P. Scales

July 18, 2006

Columbia Acorn Family of Funds Class A, B and C Share Information

Minimum Initial Investment in
Columbia Acorn International,
Columbia Acorn International
Select and Columbia
Thermostat Fund				$1,000 $1,000 for an IRA
Minimum Initial Investment in Columbia Acorn Fund and Columbia Acorn USA				$75,000
Minimum Initial Investment in Columbia Acorn Select				$50,000
Minimum Subsequent Investment in all Funds				$50
Exchange Fee				None

Columbia Acorn Fund	Class A			Class B			Class C
Management Fees		0.64	%		0.64	%		0.64	%
Distribution and Service (12b-1) Fees		0.25	%		0.85	%		1.00	%
Other Expenses		0.12	%		0.21	%		0.16	%
Net Expense Ratio		1.01	%		1.70	%		1.80	%
Columbia Acorn International	Class A			Class B			Class C
Management Fees		0.78	%		0.78	%		0.78	%
Distribution and Service (12b-1) Fees		0.25	%		0.85	%		1.00	%
Other Expenses		0.19	%		0.30	%		0.22	%
Net Expense Ratio		1.22	%		1.93	%		2.00	%
Columbia Acorn USA	Class A			Class B			Class C
Management Fees		0.87	%		0.87	%		0.87	%
Distribution and Service (12b-1) Fees		0.25	%		0.85	%		1.00	%
Other Expenses		0.13	%		0.24	%		0.18	%
Net Expense Ratio		1.25	%		1.96	%		2.05	%
Columbia Acorn International Select	Class A			Class B			Class C
Management Fees		0.94	%		0.94	%		0.94	%
Distribution and Service (12b-1) Fees		0.25	%		0.85	%		1.00	%
Other Expenses		0.41	%		0.50	%		0.46	%
Net Expense Ratio		1.60	%		2.29	%		2.40	%
Columbia Acorn Select	Class A			Class B			Class C
Management Fees		0.82	%		0.82	%		0.82	%
Distribution and Service (12b-1) Fees		0.25	%		0.85	%		1.00	%
Other Expenses		0.16	%		0.28	%		0.22	%
Net Expense Ratio		1.23	%		1.95	%		2.04	%
Columbia Thermostat*	Class A			Class B			Class C
Management Fees		0.10	%		0.10	%		0.10	%
Distribution and Service (12b-1) Fees		0.25	%		0.85	%		1.00	%
Other Expenses		0.15	%		0.15	%		0.15	%
Net Expense Ratio		0.50	%		1.10	%		1.25	%

Fees and expenses are for the six months ended June 30, 2006 and for Columbia Acorn International Select and Columbia Thermostat Fund include the effect of Columbia Wanger Asset Management's undertaking to reimburse those funds for any ordinary operating expenses (exclusive of 12b-1 service and distribution fees, interest, taxes and extraordinary expenses, if any), net of custody fees paid indirectly, exceeding 1.45% and 0.25% of their average net assets, respectively. The expense limitation for Columbia Acorn International Select is voluntary and can be terminated by Columbia Wanger Asset Management, L.P. on 30 days' notice. Columbia Thermostat Fund's reimbursement arrangement is contractual through April 30, 2007. The Funds' adviser and/or affiliates have voluntarily agreed to waive a portion of "other expenses" for the Columbia Acorn Family of Funds.

* Does not include estimated fees and expenses of 0.71% incurred by the Fund from the underlying portfolio funds.

Columbia Acorn

Family of Funds

Trustees

Robert E. Nason

Chairman

Allan B. Muchin

Vice Chairman

Margaret Eisen

Jerome Kahn, Jr.

Steven N. Kaplan

David C. Kleinman

Charles P. McQuaid

James A. Star

Ralph Wanger

Patricia H. Werhane

John A. Wing

Officers

Charles P. McQuaid

President

Ben Andrews

Vice President

Michael G. Clarke

Assistant Treasurer

Jeffrey R. Coleman

Assistant Treasurer

J. Kevin Connaughton

Assistant Treasurer

P. Zachary Egan

Vice President

John M. Kunka

Assistant Treasurer

Joseph C. LaPalm

Vice President

Bruce H. Lauer

Vice President, Treasurer and Secretary

Louis J. Mendes III

Vice President

Robert A. Mohn

Vice President

Christopher J. Olson

Vice President

Michelle H. Rhee

Assistant Secretary

Linda K. Roth-Wiszowaty

Assistant Secretary

Robert P. Scales

Senior Vice President, Chief Legal Officer
and General Counsel

Investment Adviser

Columbia Wanger Asset Management, L.P.
227 West Monroe Street, Suite 3000
Chicago, Illinois 60606

1-800-922-6769

Distributor

Columbia Management Distributors, Inc.
One Financial Center
Boston, Massachusetts 02111-2621

Transfer Agent, Dividend Disbursing Agent

Columbia Management Services, Inc.
P.O. Box 8081
Boston, Massachusetts 02266-8081

1-800-345-6611

Legal Counsel

Bell, Boyd & Lloyd LLC
Chicago, Illinois

Find out what's new – visit our web site at:

www.columbiafunds.com

Our e-mail address is:

ServiceInquiries@ColumbiaManagement.com

1-800-922-6769

Directions to the 2006 Annual Shareholder Information Meeting

From the south:

From the north:

Take the Kennedy Expressway (I-90/94) south to Chicago. Exit in the city at Monroe Street. Turn left (east) from the exit onto Monroe Street. Proceed east on Monroe Street to Dearborn.

From the west:

Take the Eisenhower Expressway (I-290) from the west. This becomes Congress Street in the city. Take Congress east to Dearborn Street. Turn left (north) on Dearborn to Monroe Street.

From the southwest:

Parking Information for 2006 Annual Shareholder Information Meeting

Join Us!

September 26, 2006

Meet your portfolio managers, analysts
and fellow shareholders

Columbia Acorn Funds
2006 Annual Shareholder
Information Meeting

Chase Auditorium
(formerly Bank One Auditorium)
38 South Dearborn Street
Chicago, IL 60602

Columbia Acorn Family of Funds

Class A, B, C Shares

Semiannual Report – June 30, 2006

PRSRT STD

U.S. POSTAGE

PAID

HOLLISTON, MA

PERMIT NO. 20

Columbia Management_®

One Financial Center, Boston, MA 02111-2621

800-345-6611 www.columbiafunds.com

SHC-44/112004-0606 (08/06) 06/28577

Item 2. Code of Ethics.

Not applicable at this time.

Item 3. Audit Committee Financial Expert.

Not applicable at this time.

Item 4. Principal Accountant Fees and Services.

Not applicable at this time.

Item 5. Audit Committee of Listed Registrants.

Not applicable.

Item 6. Schedule of Investments

The registrant’s “Schedule I – Investments in securities of unaffiliated issuers” (as set forth in 17 CFR 210.12-12) is included in Item 1 of this Form N-CSR.

Item 7. Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies.

Not applicable.

Item 8. Portfolio Managers of Closed-End Management Investment Companies.

Not applicable.

Item 9. Purchases of Equity Securities by Closed-End Management Investment Company and Affiliated Purchasers.

Not applicable.

Item 10. Submission of Matters to a Vote of Security Holders.

There have not been any material changes to the procedures by which shareholders may recommend nominees to the registrant’s board of directors, since those procedures were

last disclosed in response to the requirements of Item 7(d)(2)(ii)(G) of Schedule 14A or this Item.

Item 11. Controls and Procedures.

(a) The registrant’s principal executive officer and principal financial officers, based on their evaluation of the registrant’s disclosure controls and procedures as of a date within 90 days of the filing of this report, have concluded that such controls and procedures are adequately designed to ensure that information required to be disclosed by the registrant in Form N-CSR is accumulated and communicated to the registrant’s management, including the principal executive officer and principal financial officer, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure.

(b) There were no changes in the registrant’s internal control over financial reporting that occurred during the registrant’s second fiscal quarter of the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting.

Item 12. Exhibits.

(a)(1) Code of ethics required to be disclosed under Item 2 of Form N-CSR: Not applicable at this time.

(a)(2) Certifications pursuant to Rule 30a-2(a) under the Investment Company Act of 1940 (17 CFR 270.30a-2(a)) attached hereto as Exhibit 99.CERT.

(a)(3) Not applicable.

(b) Certification pursuant to Rule 30a-2(b) under the Investment Company Act of 1940 (17 CFR 270.30a-2(b)) attached hereto as Exhibit 99.906CERT.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

(registrant)		Columbia Acorn Trust


By (Signature and Title)	/s/	Charles P. McQuaid
		Charles P. McQuaid, President


Date		August 25, 2006

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

By (Signature and Title)	/s/	Charles P. McQuaid
		Charles P. McQuaid, President


Date		August 25, 2006


By (Signature and Title)	/s/	Bruce H. Lauer
		Bruce H. Lauer, Treasurer


Date		August 25, 2006