497

The interactive data file included as an exhibit to this filing relates to the supplement to the prospectuses for Columbia Acorn USA filed pursuant to Rule 497(e) under the Securities Act of 1933, as amended, on June 27, 2016 (Accession No. 0001193125-16-632767), which is incorporated herein by reference.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	Other
Document Period End Date	dei_DocumentPeriodEndDate	Dec. 31, 2015
Registrant Name	dei_EntityRegistrantName	COLUMBIA ACORN TRUST
Central Index Key	dei_EntityCentralIndexKey	0000002110
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Jun. 27, 2016
Document Effective Date	dei_DocumentEffectiveDate	Jun. 27, 2016
Prospectus Date	rr_ProspectusDate	May 01, 2016

XML

May 01, 2016

Supplement dated June 27, 2016

to the Prospectus and Summary Prospectus of the following Fund:

Fund	Prospectus and Summary Prospectus Dated
Columbia Acorn Trust
Columbia Acorn USA®	5/1/2016

1. The table under the caption “Fees and Expenses of the Fund” in the “Summary of the Fund” section of the Prospectus and the Summary Prospectus is hereby superseded and replaced with the following:

Shareholder Fees (fees paid directly from your investment)
	Class A	Class C	Classes I, R4, R5, Y and Z
Maximum sales charge (load) imposed on purchases (as a % of offering price)	5.75%	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% (a)	1.00% (b)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class C	Class I	Class R4	Class R5	Class Y	Class Z
Management fees(c)	0.89%	0.89%	0.89%	0.89%	0.89%	0.89%	0.89%
Distribution and/or service (12b-1) fees	0.25%	1.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Other expenses(d)	0.29%	0.29%	0.14%	0.29%	0.19%	0.14%	0.29%
Total annual Fund operating expenses	1.43%	2.18%	1.03%	1.18%	1.08%	1.03%	1.18%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.
(b)	This charge applies to redemptions within 12 months after purchase, with certain limited exceptions.
(c)	Management fees have been restated to reflect current fees based on current asset levels.
(d)	Other expenses have been restated and are based on estimated amounts for the Fund’s current fiscal year, taking into consideration changes in the Fund’s net assets and changes in the method of allocating transfer agent expenses among Class A, Class C, Class R4 and Class Z shares of the Fund.
2.	The expense example table that appears under the caption “Fees and Expenses of the Fund – Example” in the “Summary of the Fund” section of the Prospectus and the Summary Prospectus is hereby superseded and replaced with the following:

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$712	$1,001	$1,312	$2,190
Class C (assuming redemption of all shares at the end of the period)	$321	$ 682	$1,169	$2,513
Class C (assuming no redemption of shares)	$221	$ 682	$1,169	$2,513
Class I (whether or not shares are redeemed)	$105	$ 328	$ 569	$1,259
Class R4 (whether or not shares are redeemed)	$120	$ 375	$ 649	$1,432
Class R5 (whether or not shares are redeemed)	$110	$ 343	$ 595	$1,317
Class Y (whether or not shares are redeemed)	$105	$ 328	$ 569	$1,259
Class Z (whether or not shares are redeemed)	$120	$ 375	$ 649	$1,432

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

COLUMBIA ACORN TRUST

Prospectus Date

rr_ProspectusDate

May 01, 2016

Supplement [Text Block]

cat6_SupplementTextBlock

Supplement dated June 27, 2016

to the Prospectus and Summary Prospectus of the following Fund:

Fund	Prospectus and Summary Prospectus Dated
Columbia Acorn Trust
Columbia Acorn USA®	5/1/2016

1. The table under the caption “Fees and Expenses of the Fund” in the “Summary of the Fund” section of the Prospectus and the Summary Prospectus is hereby superseded and replaced with the following:

Shareholder Fees (fees paid directly from your investment)
	Class A	Class C	Classes I, R4, R5, Y and Z
Maximum sales charge (load) imposed on purchases (as a % of offering price)	5.75%	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% (a)	1.00% (b)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class C	Class I	Class R4	Class R5	Class Y	Class Z
Management fees(c)	0.89%	0.89%	0.89%	0.89%	0.89%	0.89%	0.89%
Distribution and/or service (12b-1) fees	0.25%	1.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Other expenses(d)	0.29%	0.29%	0.14%	0.29%	0.19%	0.14%	0.29%
Total annual Fund operating expenses	1.43%	2.18%	1.03%	1.18%	1.08%	1.03%	1.18%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.
(b)	This charge applies to redemptions within 12 months after purchase, with certain limited exceptions.
(c)	Management fees have been restated to reflect current fees based on current asset levels.
(d)	Other expenses have been restated and are based on estimated amounts for the Fund’s current fiscal year, taking into consideration changes in the Fund’s net assets and changes in the method of allocating transfer agent expenses among Class A, Class C, Class R4 and Class Z shares of the Fund.
2.	The expense example table that appears under the caption “Fees and Expenses of the Fund – Example” in the “Summary of the Fund” section of the Prospectus and the Summary Prospectus is hereby superseded and replaced with the following:

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$712	$1,001	$1,312	$2,190
Class C (assuming redemption of all shares at the end of the period)	$321	$ 682	$1,169	$2,513
Class C (assuming no redemption of shares)	$221	$ 682	$1,169	$2,513
Class I (whether or not shares are redeemed)	$105	$ 328	$ 569	$1,259
Class R4 (whether or not shares are redeemed)	$120	$ 375	$ 649	$1,432
Class R5 (whether or not shares are redeemed)	$110	$ 343	$ 595	$1,317
Class Y (whether or not shares are redeemed)	$105	$ 328	$ 569	$1,259
Class Z (whether or not shares are redeemed)	$120	$ 375	$ 649	$1,432

Columbia Acorn USA

Risk/Return:

rr_RiskReturnAbstract

Supplement [Text Block]

cat6_SupplementTextBlock

Supplement dated June 27, 2016

to the Prospectus and Summary Prospectus of the following Fund:

Fund	Prospectus and Summary Prospectus Dated
Columbia Acorn Trust
Columbia Acorn USA®	5/1/2016

1. The table under the caption “Fees and Expenses of the Fund” in the “Summary of the Fund” section of the Prospectus and the Summary Prospectus is hereby superseded and replaced with the following:

Shareholder Fees (fees paid directly from your investment)
	Class A	Class C	Classes I, R4, R5, Y and Z
Maximum sales charge (load) imposed on purchases (as a % of offering price)	5.75%	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% (a)	1.00% (b)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class C	Class I	Class R4	Class R5	Class Y	Class Z
Management fees(c)	0.89%	0.89%	0.89%	0.89%	0.89%	0.89%	0.89%
Distribution and/or service (12b-1) fees	0.25%	1.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Other expenses(d)	0.29%	0.29%	0.14%	0.29%	0.19%	0.14%	0.29%
Total annual Fund operating expenses	1.43%	2.18%	1.03%	1.18%	1.08%	1.03%	1.18%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.
(b)	This charge applies to redemptions within 12 months after purchase, with certain limited exceptions.
(c)	Management fees have been restated to reflect current fees based on current asset levels.
(d)	Other expenses have been restated and are based on estimated amounts for the Fund’s current fiscal year, taking into consideration changes in the Fund’s net assets and changes in the method of allocating transfer agent expenses among Class A, Class C, Class R4 and Class Z shares of the Fund.
2.	The expense example table that appears under the caption “Fees and Expenses of the Fund – Example” in the “Summary of the Fund” section of the Prospectus and the Summary Prospectus is hereby superseded and replaced with the following:

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$712	$1,001	$1,312	$2,190
Class C (assuming redemption of all shares at the end of the period)	$321	$ 682	$1,169	$2,513
Class C (assuming no redemption of shares)	$221	$ 682	$1,169	$2,513
Class I (whether or not shares are redeemed)	$105	$ 328	$ 569	$1,259
Class R4 (whether or not shares are redeemed)	$120	$ 375	$ 649	$1,432
Class R5 (whether or not shares are redeemed)	$110	$ 343	$ 595	$1,317
Class Y (whether or not shares are redeemed)	$105	$ 328	$ 569	$1,259
Class Z (whether or not shares are redeemed)	$120	$ 375	$ 649	$1,432

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

Management fees have been restated to reflect current fees based on current asset levels.

Other expenses have been restated and are based on estimated amounts for the Fund’s current fiscal year, taking into consideration changes in the Fund’s net assets and changes in the method of allocating transfer agent expenses among Class A, Class C, Class R4 and Class Z shares of the Fund.

Columbia Acorn USA | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.75%

Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[1]

Management fees

rr_ManagementFeesOverAssets

0.89%

^[2]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.29%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.43%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.

1 year

rr_ExpenseExampleYear01

$ 712

3 years

rr_ExpenseExampleYear03

1,001

5 years

rr_ExpenseExampleYear05

1,312

10 years

rr_ExpenseExampleYear10

2,190

1 year

rr_ExpenseExampleNoRedemptionYear01

712

3 years

rr_ExpenseExampleNoRedemptionYear03

1,001

5 years

rr_ExpenseExampleNoRedemptionYear05

1,312

10 years

rr_ExpenseExampleNoRedemptionYear10

$ 2,190

Columbia Acorn USA | Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[4]

Management fees

rr_ManagementFeesOverAssets

0.89%

^[2]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.29%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

2.18%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

This charge applies to redemptions within 12 months after purchase, with certain limited exceptions.

1 year

rr_ExpenseExampleYear01

$ 321

3 years

rr_ExpenseExampleYear03

682

5 years

rr_ExpenseExampleYear05

1,169

10 years

rr_ExpenseExampleYear10

2,513

1 year

rr_ExpenseExampleNoRedemptionYear01

221

3 years

rr_ExpenseExampleNoRedemptionYear03

682

5 years

rr_ExpenseExampleNoRedemptionYear05

1,169

10 years

rr_ExpenseExampleNoRedemptionYear10

$ 2,513

Columbia Acorn USA | Class I

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)

rr_MaximumDeferredSalesChargeOverOther

none

Management fees

rr_ManagementFeesOverAssets

0.89%

^[2]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.14%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.03%

1 year

rr_ExpenseExampleYear01

$ 105

3 years

rr_ExpenseExampleYear03

328

5 years

rr_ExpenseExampleYear05

569

10 years

rr_ExpenseExampleYear10

1,259

1 year

rr_ExpenseExampleNoRedemptionYear01

105

3 years

rr_ExpenseExampleNoRedemptionYear03

328

5 years

rr_ExpenseExampleNoRedemptionYear05

569

10 years

rr_ExpenseExampleNoRedemptionYear10

$ 1,259

Columbia Acorn USA | Class R4

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)

rr_MaximumDeferredSalesChargeOverOther

none

Management fees

rr_ManagementFeesOverAssets

0.89%

^[2]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.29%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.18%

1 year

rr_ExpenseExampleYear01

$ 120

3 years

rr_ExpenseExampleYear03

375

5 years

rr_ExpenseExampleYear05

649

10 years

rr_ExpenseExampleYear10

1,432

1 year

rr_ExpenseExampleNoRedemptionYear01

120

3 years

rr_ExpenseExampleNoRedemptionYear03

375

5 years

rr_ExpenseExampleNoRedemptionYear05

649

10 years

rr_ExpenseExampleNoRedemptionYear10

$ 1,432

Columbia Acorn USA | Class R5

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)

rr_MaximumDeferredSalesChargeOverOther

none

Management fees

rr_ManagementFeesOverAssets

0.89%

^[2]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.19%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.08%

1 year

rr_ExpenseExampleYear01

$ 110

3 years

rr_ExpenseExampleYear03

343

5 years

rr_ExpenseExampleYear05

595

10 years

rr_ExpenseExampleYear10

1,317

1 year

rr_ExpenseExampleNoRedemptionYear01

110

3 years

rr_ExpenseExampleNoRedemptionYear03

343

5 years

rr_ExpenseExampleNoRedemptionYear05

595

10 years

rr_ExpenseExampleNoRedemptionYear10

$ 1,317

Columbia Acorn USA | Class Y

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)

rr_MaximumDeferredSalesChargeOverOther

none

Management fees

rr_ManagementFeesOverAssets

0.89%

^[2]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.14%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.03%

1 year

rr_ExpenseExampleYear01

$ 105

3 years

rr_ExpenseExampleYear03

328

5 years

rr_ExpenseExampleYear05

569

10 years

rr_ExpenseExampleYear10

1,259

1 year

rr_ExpenseExampleNoRedemptionYear01

105

3 years

rr_ExpenseExampleNoRedemptionYear03

328

5 years

rr_ExpenseExampleNoRedemptionYear05

569

10 years

rr_ExpenseExampleNoRedemptionYear10

$ 1,259

Columbia Acorn USA | Class Z

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)

rr_MaximumDeferredSalesChargeOverOther

none

Management fees

rr_ManagementFeesOverAssets

0.89%

^[2]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.29%

^[3]

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.18%

1 year

rr_ExpenseExampleYear01

$ 120

3 years

rr_ExpenseExampleYear03

375

5 years

rr_ExpenseExampleYear05

649

10 years

rr_ExpenseExampleYear10

1,432

1 year

rr_ExpenseExampleNoRedemptionYear01

120

3 years

rr_ExpenseExampleNoRedemptionYear03

375

5 years

rr_ExpenseExampleNoRedemptionYear05

649

10 years

rr_ExpenseExampleNoRedemptionYear10

$ 1,432

[1] This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.

[2] Management fees have been restated to reflect current fees based on current asset levels.

[3] Other expenses have been restated and are based on estimated amounts for the Fund's current fiscal year, taking into consideration changes in the Fund's net assets and changes in the method of allocating transfer agent expenses among Class A, Class C, Class R4 and Class Z shares of the Fund.

[4] This charge applies to redemptions within 12 months after purchase, with certain limited exceptions.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	COLUMBIA ACORN TRUST
Prospectus Date	rr_ProspectusDate	May 01, 2016
Document Creation Date	dei_DocumentCreationDate	Jun. 27, 2016