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: 811-07177

Name of Fund: BlackRock Mid Cap Dividend Fund of BlackRock Mid Cap Dividend Series, Inc.

Fund Address:  100 Bellevue Parkway, Wilmington, DE 19809

Name and address of agent for service: John M. Perlowski, Chief Executive Officer, BlackRock Mid Cap Dividend Fund of BlackRock Mid Cap Dividend Series, Inc., 55 East 52^nd Street, New York, NY 10055

Registrant’s telephone number, including area code: (800) 441-7762

Date of fiscal year end: 01/31/2019

Date of reporting period: 07/31/2018

Item 1 – Report to Stockholders

JULY 31, 2018

SEMI-ANNUAL REPORT (UNAUDITED)

BlackRock Mid Cap Dividend Series, Inc.

^Ø  BlackRock Mid Cap Dividend Fund

Not FDIC Insured • May Lose Value • No Bank Guarantee

The Markets in Review

Dear Shareholder,

In the 12 months ended July 31, 2018, the strongest corporate profits in seven years drove the equity market higher, while rising interest rates constrained bond returns. Though the market’s appetite for risk remained healthy, risk-taking was tempered somewhat, as shorter-term, higher-quality securities led the bond market, and U.S. equities outperformed most international stock markets.

Strong equity performance worldwide was driven by synchronized economic growth across the most influential economies. However, volatility in emerging market stocks rose, as U.S.-China trade relations and debt concerns weighed heavily on the Chinese stock market, while Turkey became embroiled in a currency crisis shortly after the end of the reporting period.

Short-term U.S. Treasury interest rates rose the fastest, while longer-term rates slightly increased, leading to a negative return for long-term U.S. Treasuries and a substantial flattening of the yield curve. Many investors are concerned with the flattening yield curve as a harbinger of recession, but given the extraordinary monetary measures in the last decade, we believe a more accurate barometer for the economy is the returns along the risk spectrums in stock and bond markets. Although the fundamentals in credit markets remained relatively solid, investment-grade bonds declined slightly, and high-yield bonds posted modest returns.

In response to rising growth and inflation, the U.S. Federal Reserve (the “Fed”) increased short-term interest rates three times during the reporting period. The Fed also reduced its $4.3 trillion balance sheet by approximately $180 billion during the reporting period, gradually reversing the unprecedented stimulus measures it enacted after the financial crisis. Meanwhile, the European Central Bank announced that its bond-purchasing program would conclude at the end of the year, while also expressing its commitment to low interest rates. In contrast, the Bank of Japan continued to expand its balance sheet through bond purchasing while lowering its expectations for inflation.

The U.S. economy continued to gain momentum despite the Fed’s modest reduction of economic stimulus; unemployment declined to 3.9%, wages increased, and the number of job openings reached a record high. Strong economic performance may justify a more rapid pace of rate hikes in 2018, as the headline inflation rate and investors’ expectations for inflation have already surpassed the Fed’s target of 2.0%.

While U.S. monetary policy is seeking to restrain economic growth and inflation, fiscal policy has produced new sources of growth that could nourish the economy for the next few years. Corporate tax cuts and repatriation of capital held abroad could encourage a virtuous cycle of business spending. Lower individual tax rates coupled with the robust job market may refresh consumer spending.

We continue to believe the primary risks to economic expansion are trade protectionism, rapidly rising interest rates, and geopolitical tension. Given the deflationary forces of technology and globalization, a substantial increase in inflation is unlikely to materialize as long as the unemployment rate remains above 3.0%. However, we are closely monitoring trade protectionism and the rise of populism in Western nations. In particular, the outcome of trade negotiations between the United States and China is likely to influence the global growth trajectory and set the tone for free trade in many other nations.

In this environment, investors need to think globally, extend their scope across a broad array of asset classes, and be nimble as market conditions change. We encourage you to talk with your financial advisor and visit blackrock.com for further insight about investing in today’s markets.

Sincerely,

Rob Kapito

President, BlackRock Advisors, LLC

Rob Kapito

President, BlackRock Advisors, LLC

Total Returns as of July 31, 2018
	6-month	12-month
U.S. large cap equities (S&P 500® Index)	0.70%	16.24%
U.S. small cap equities (Russell 2000® Index)	6.75	18.73
International equities (MSCI Europe, Australasia, Far East Index)	(5.12)	6.40
Emerging market equities (MSCI Emerging Markets Index)	(11.94)	4.36
3-month Treasury bills (ICE BofAML 3-Month U.S. Treasury Bill Index)	0.85	1.43
U.S. Treasury securities (ICE BofAML 10-Year U.S. Treasury Index)	(0.95)	(3.66)
U.S. investment grade bonds (Bloomberg Barclays U.S. Aggregate Bond Index)	(0.45)	(0.80)
Tax-exempt municipal bonds (S&P Municipal Bond Index)	1.20	1.21
U.S. high yield bonds (Bloomberg Barclays U.S. Corporate High Yield 2% Issuer Capped Index)	0.65	2.60
Past performance is no guarantee of future results. Index performance is shown for illustrative purposes only. You cannot invest directly in an index.

2 THIS PAGE IS NOT PART OF YOUR FUND REPORT

Table of Contents

	Page
The Markets in Review		2
Semi-Annual Report:
Fund Summary		4
About Fund Performance		6
Disclosure of Expenses		6
Derivative Financial Instruments		6
Financial Statements:
Schedule of Investments		7
Statement of Assets and Liabilities		10
Statement of Operations		11
Statements of Changes in Net Assets		12
Financial Highlights		13
Notes to Financial Statements		18
Disclosure of Investment Advisory Agreement		26
Director and Officer Information		29
Additional Information		30

3

Fund Summary  as of July 31, 2018 BlackRock Mid Cap Dividend Fund

Investment Objective

BlackRock Mid Cap Dividend Fund’s (the “Fund”) investment objective is to seek capital appreciation and, secondarily, income, by investing in securities, primarily equity securities that the Fund’s management believes are undervalued and therefore represent an investment value.

Portfolio Management Commentary

How did the Fund perform?

For the six-month period ended July 31, 2018, the Fund outperformed its benchmark, the Russell Midcap^® Value Index.

What factors influenced performance?

The largest contribution to relative performance during the period derived from a combination of stock selection within and an overweight to the information technology (“IT”) sector. Notably, stock selection in the technology hardware, storage & peripherals and software industries proved beneficial, as did an overweight to electronic equipment, instruments & components. Within the financials sector, stock selection in the banking industry and an underweight to consumer finance boosted relative performance. Lastly, a combination of stock selection within and an underweight to consumer discretionary added to relative return.

The largest detractor from relative performance came from a combination of stock selection and allocation decisions within the real estate sector. Notably, an underweight to equity real estate investment trusts weighed on relative return, as did stock selection in the real estate management & development industry. Within the health care sector, a combination of stock selection within and an overweight to health care providers & services detracted from relative return, as did stock selection in biotechnology and pharmaceuticals. Lastly, stock selection in industrials weighed on returns.

Describe recent portfolio activity.

During the six-month period, the portfolio’s exposure to financials and industrials increased, while exposure to the IT and consumer discretionary sectors decreased.

Describe portfolio positioning at period end.

At the end of the period, the Fund’s largest allocations were in the financials, health care and IT sectors. Relative to the Russell MidCap^® Value Index benchmark, the largest overweight positions were in financials, health care and IT. Conversely, the largest relative underweights were in the real estate, consumer discretionary and industrials sectors.

The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.

Portfolio Information

TEN LARGEST HOLDINGS

Security	Percent of Net Assets
Brighthouse Financial, Inc.		3	%
CDW Corp.		3
Regions Financial Corp.		2
SunTrust Banks, Inc.		2
BlackRock Liquidity Funds, T-Fund, Institutional Class		2
FirstEnergy Corp.		2
KeyCorp		2
Hess Corp.		2
Lamar Advertising Co.		2
Telephone & Data Systems, Inc.		2

SECTOR ALLOCATION

Sector	Percent of Net Assets
Financials		23	%
Information Technology		12
Health Care		11
Utilities		9
Energy		8
Industrials		8
Consumer Discretionary		7
Real Estate		7
Materials		6
Consumer Staples		5
Telecommunication Services		2
Short-Term Securities		2
Liabilities in Excess of Other Assets		—	(a)

For Fund compliance purposes, the Fund’s sector classifications refer to one or more of the sector sub-classifications used by one or more widely recognized market indexes or rating group indexes, and/or as defined by the investment adviser. These definitions may not apply for purposes of this report, which may combine such sector sub-classifications for reporting ease.

^(a) Amount is less than 1%.

4 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Fund Summary  as of July 31, 2018 (continued) BlackRock Mid Cap Dividend Fund

Performance Summary for the Period Ended July 31, 2018

				Average Annual Total Returns (a)(b)
				1 Year						5 Years						10 Years
	6-Month Total Returns			w/o sales charge			w/sales charge			w/o sales charge			w/sales charge			w/o sales charge			w/sales charge
Institutional		0.84	%		12.17	%		N/A			8.74	%		N/A			9.48	%		N/A
Investor A		0.75			11.99			6.11	%		8.45			7.29	%		9.14			8.55	%
Investor C		0.32			11.10			10.10			7.59			7.59			8.17			8.17
Class K		0.86			12.20			N/A			8.75			N/A			9.48			N/A
Class R		0.57			11.65			N/A			8.13			N/A			8.77			N/A
Russell Midcap® Value Index(c)		0.25			9.07			N/A			10.71			N/A			10.49			N/A

^(a)  Assuming maximum sales charges, if any. Average annual total returns with and without sales charges reflect reductions for distribution and service fees. See “About Fund Performance” on page 6 for a detailed description of share classes, including any related sales charges and fees, and how performance was calculated for certain share classes.

^(b) Under normal circumstances, the Fund invests at least 80% of its net assets plus the amount of any borrowings for investment purposes in equity securities of mid cap companies and at least 80% of its net assets plus the amount of any borrowings for investment purposes in dividend-paying securities. The Fund’s total returns prior to June 12, 2017 are the returns of the Fund when it followed different investment strategies under the name BlackRock Mid Cap Value Opportunities Fund.

^(c) An unmanaged index that measures the performance of the mid-capitalization value sector of the U.S. equity market. It is a subset of the Russell Midcap^® Index, which measures the performance of the mid-capitalization sector of the U.S. equity market. The Russell Midcap^® Value Index measures the performance of equity securities of Russell Midcap^® Index issuers with relatively lower price-to-book ratios and lower forecasted growth. The Russell Midcap^® Index is a float-adjusted, capitalization-weighted index of approximately 793 of the smallest issuers in the Russell 1000^® Index and includes securities issued by issuers which range in size between approximately $10 million and $85 billion, although this range may change from time to time.

N/A — Not applicable as share class and index do not have a sales charge.

Past performance is not indicative of future results.

Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles.

Expense Example

	Actual						Hypothetical (b)
	Beginning Account Value (02/01/18)		Ending Account Value (07/31/18)		Expenses Paid During the Period (a)		Beginning Account Value (02/01/18)		Ending Account Value (07/31/18)		Expenses Paid During the Period (a)		Annualized Expense Ratio
Institutional	$	1,000.00	$	1,008.40	$	4.28	$	1,000.00	$	1,020.53	$	4.31		0.86	%
Investor A		1,000.00		1,007.50		5.53		1,000.00		1,019.29		5.56		1.11
Investor C		1,000.00		1,003.20		9.24		1,000.00		1,015.57		9.30		1.86
Class K		1,000.00		1,008.60		3.98		1,000.00		1,020.83		4.01		0.80
Class R		1,000.00		1,005.70		6.76		1,000.00		1,018.05		6.80		1.36

^(a)  For each class of the Fund, expenses are equal to the annualized net expense ratio for the class, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period shown).

^(b)  Hypothetical 5% annual return before expenses is calculated by prorating the number of days in the most recent fiscal half year divided by 365.

See “Disclosure of Expenses” on page 7 for further information on how expenses were calculated.

FUND SUMMARY 5

About Fund Performance

Institutional Shares and Class K Shares are not subject to any sales charge. These shares bear no ongoing distribution or service fees and are available only to certain eligible investors. Class K Share performance shown prior to the January 25, 2018 inception date is that of Institutional Shares. The performance of the Fund’s Class K Shares would be substantially similar to Institutional Shares because Class K Shares and Institutional Shares invest in the same portfolio of securities and performance would only differ to the extent that Class K Shares and Institutional Shares have different expenses. The actual returns of Class K Shares would have been higher than those of the Institutional Shares because Class K Shares have lower expenses than the Institutional Shares.

Investor A Shares are subject to a maximum initial sales charge (front-end load) of 5.25% and a service fee of 0.25% per year (but no distribution fee). Certain redemptions of these shares may be subject to a contingent deferred sales charge (“CDSC”) where no initial sales charge was paid at the time of purchase. These shares are generally available through financial intermediaries.

Investor C Shares are subject to a 1.00% CDSC if redeemed within one year of purchase. In addition, these shares are subject to a distribution fee of 0.75% per year and a service fee of 0.25% per year. These shares are generally available through financial intermediaries.

Class R Shares are not subject to any sales charge. These shares are subject to a distribution fee of 0.25% per year and a service fee of 0.25% per year. These shares are available only to certain employer-sponsored retirement plans.

Performance information reflects past performance and does not guarantee future results. Current performance may be lower or higher than the performance data quoted. Refer to www.blackrock.com to obtain performance data current to the most recent month-end. Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares. Figures shown in the performance tables on page 5 assume reinvestment of all distributions, if any, at net asset value on the ex-dividend date. Investment return and principal value of shares will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Distributions paid to each class of shares will vary because of the different levels of service, distribution and transfer agency fees applicable to each class, which are deducted from the income available to be paid to shareholders.

BlackRock Advisors, LLC (the “Manager”), the Fund’s investment adviser, contractually and voluntarily waived and/or reimbursed a portion of the Fund’s expenses. Without such waiver and/or reimbursement, the Fund’s performance would have been lower. The Manager is under no obligation to waive and/or reimburse or to continue waiving and/or reimbursing its fees and such voluntary waiver and/or reimbursement may be reduced or discontinued at any time. See Note 6 of the Notes to Financial Statements for additional information on waivers and/or reimbursements.

Disclosure of Expenses

Shareholders of the Fund may incur the following charges: (a) transactional expenses, such as sales charges; and (b) operating expenses, including investment advisory fees, service and distribution fees, including 12b-1 fees, acquired fund fees and expenses and other fund expenses. The expense example shown on page 5 (which is based on a hypothetical investment of $1,000 invested on February 1, 2018 and held through July 31, 2018 except with respect to the Fund’s Class K Shares which are based on a hypothetical investment of $1,000 on January 25, 2018 (commencement of operations) and held through January 31, 2018) is intended to assist shareholders both in calculating expenses based on an investment in the Fund and in comparing these expenses with similar costs of investing in other mutual funds held through July 31, 2018.

The expense example provides information about actual account values and actual expenses. In order to estimate the expenses a shareholder paid during the period covered by this report, shareholders can divide their account value by $1,000 and then multiply the result by the number corresponding to their Fund and share class under the heading entitled “Expenses Paid During the Period.”

The expense example also provides information about hypothetical account values and hypothetical expenses based on the Fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses. In order to assist shareholders in comparing the ongoing expenses of investing in the Fund and other funds, compare the 5% hypothetical example with the 5% hypothetical examples that appear in shareholder reports of other funds.

The expenses shown in the expense example are intended to highlight shareholders’ ongoing costs only and do not reflect any transactional expenses, such as sales charges, if any. Therefore, the hypothetical example is useful in comparing ongoing expenses only, and will not help shareholders determine the relative total expenses of owning different funds. If these transactional expenses were included, shareholder expenses would have been higher.

Derivative Financial Instruments

The Fund may invest in various derivative financial instruments. These instruments are used to obtain exposure to a security, commodity, index, market, and/or other assets without owning or taking physical custody of securities, commodities and/or other referenced assets or to manage market, equity, credit, interest rate, foreign currency exchange rate, commodity and/or other risks. Derivative financial instruments may give rise to a form of economic leverage and involve risks, including the imperfect correlation between the value of a derivative financial instrument and the underlying asset, possible default of the counterparty to the transaction or illiquidity of the instrument. The Fund’s successful use of a derivative financial instrument depends on the investment adviser’s ability to predict pertinent market movements accurately, which cannot be assured. The use of these instruments may result in losses greater than if they had not been used, may limit the amount of appreciation the Fund can realize on an investment and/or may result in lower distributions paid to shareholders. The Fund’s investments in these instruments, if any, are discussed in detail in the Notes to Financial Statements.

6 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Schedule of Investments  (unaudited) July 31, 2018 BlackRock Mid Cap Dividend Fund (Percentages shown are based on Net Assets)

Security	Shares		Value
Common Stocks — 97.9%
Auto Components — 0.8%
Adient PLC		36,509	$	1,738,924
Magna International, Inc.		20,409		1,240,459
				2,979,383
Automobiles — 0.4%
Ford Motor Co.		157,558		1,581,882
Banks — 9.7%
Cullen/Frost Bankers, Inc.		36,299		4,010,676
KeyCorp		359,823		7,509,506
Popular, Inc.		126,270		6,266,780
Regions Financial Corp.		465,385		8,660,815
SunTrust Banks, Inc.		118,994		8,575,898
				35,023,675
Beverages — 0.1%
Keurig Dr Pepper, Inc.		20,194		484,858
Building Products — 1.8%
Johnson Controls International PLC		73,670		2,763,362
Owens Corning		57,262		3,562,841
				6,326,203
Capital Markets — 0.7%
Blackstone Group LP		71,117		2,483,406
Chemicals — 2.7%
Cabot Corp.		31,348		2,072,103
Eastman Chemical Co.		51,380		5,323,996
Huntsman Corp.		72,018		2,414,763
				9,810,862
Commercial Services & Supplies — 0.5%
KAR Auction Services, Inc.		32,924		1,957,332
Communications Equipment — 1.0%
Motorola Solutions, Inc.		23,299		2,826,169
Telefonaktiebolaget LM Ericsson, Class B		112,700		884,723
				3,710,892
Construction Materials — 0.7%
CRH PLC		69,885		2,387,243
Containers & Packaging — 2.1%
International Paper Co.		45,541		2,446,918
Packaging Corp. of America		15,927		1,798,158
WestRock Co.		58,674		3,401,919
				7,646,995
Diversified Consumer Services — 0.5%
H&R Block, Inc.		67,654		1,702,175
Diversified Financial Services — 1.7%
AXA Equitable Holdings, Inc.(a)		52,566		1,155,926
Jefferies Financial Group, Inc.		197,426		4,787,581
				5,943,507
Diversified Telecommunication Services — 0.4%
BCE, Inc.		37,030		1,571,183
Electric Utilities — 7.2%
Edison International		86,951		5,793,545
Entergy Corp.		42,522		3,456,188
Evergy, Inc.		73,164		4,103,769
Exelon Corp.		20,990		892,075
FirstEnergy Corp.		226,599		8,028,403
PG&E Corp.		84,092		3,622,683
				25,896,663

Security	Shares		Value
Electrical Equipment — 1.0%
Hubbell, Inc.		16,690	$	2,057,043
nVent Electric PLC(a)		51,243		1,404,058
				3,461,101
Electronic Equipment, Instruments & Components — 5.2%
Avnet, Inc.		122,030		5,351,015
CDW Corp.		113,517		9,545,645
Dolby Laboratories, Inc., Class A		31,719		2,044,290
TE Connectivity Ltd.		20,416		1,910,325
				18,851,275
Energy Equipment & Services — 0.8%
Baker Hughes a GE Co.		31,497		1,089,166
Halliburton Co.		39,214		1,663,458
				2,752,624
Equity Real Estate Investment Trusts (REITs) — 6.2%
Crown Castle International Corp.		30,501		3,380,426
Duke Realty Corp.		58,737		1,710,421
Lamar Advertising Co., Class A		93,792		6,905,905
Prologis, Inc.		94,360		6,191,903
Rayonier, Inc.		40,774		1,427,498
Welltower, Inc.		45,407		2,842,478
				22,458,631
Food & Staples Retailing — 0.6%
Kroger Co.		74,909		2,172,361
Food Products — 2.3%
Bunge Ltd.		41,368		2,859,770
General Mills, Inc.		29,648		1,365,587
Ingredion, Inc.		22,632		2,292,621
Kellogg Co.		24,934		1,771,062
				8,289,040
Health Care Equipment & Supplies — 4.2%
Koninklijke Philips NV		128,614		5,646,096
Smith & Nephew PLC, ADR		126,180		4,430,180
Zimmer Biomet Holdings, Inc.		41,833		5,250,878
				15,327,154
Health Care Providers & Services — 5.5%
AmerisourceBergen Corp.		11,319		926,234
Cardinal Health, Inc.		40,446		2,020,278
Cigna Corp.		11,632		2,087,013
Express Scripts Holding Co.(a)		46,302		3,679,157
Humana, Inc.		19,478		6,119,598
Laboratory Corp. of America Holdings(a)		7,836		1,373,964
McKesson Corp.		17,067		2,143,615
Quest Diagnostics, Inc.		15,635		1,684,202
				20,034,061
Household Durables — 1.3%
Newell Brands, Inc.		131,729		3,449,982
Whirlpool Corp.		10,259		1,344,955
				4,794,937
Household Products — 0.9%
Energizer Holdings, Inc.		50,815		3,235,899
Independent Power and Renewable Electricity Producers — 0.8%
AES Corp.		209,797		2,802,888
Insurance — 11.1%
Allstate Corp.		25,360		2,412,243
Arthur J Gallagher & Co.		78,068		5,570,152
Assurant, Inc.		47,558		5,245,647
Assured Guaranty Ltd.		134,138		5,220,651
Brighthouse Financial, Inc.(a)		239,925		10,419,943
Everest Re Group Ltd.		6,152		1,343,289

SCHEDULE OF INVESTMENTS 7

Schedule of Investments  (unaudited) (continued) July 31, 2018 BlackRock Mid Cap Dividend Fund (Percentages shown are based on Net Assets)

Security	Shares		Value
Insurance (continued)
Hartford Financial Services Group, Inc.		58,742	$	3,095,703
Marsh & McLennan Cos., Inc.		31,218		2,602,332
MetLife, Inc.		77,717		3,554,776
Travelers Cos., Inc.		6,111		795,286
				40,260,022
IT Services — 2.0%
Cognizant Technology Solutions Corp., Class A		42,499		3,463,669
Fidelity National Information Services, Inc.		35,264		3,636,776
				7,100,445
Leisure Products — 1.0%
Mattel, Inc.		102,984		1,634,356
Polaris Industries, Inc.		17,982		1,895,663
				3,530,019
Machinery — 2.6%
Allison Transmission Holdings, Inc.		126,261		5,934,267
Pentair PLC		50,657		2,261,835
Stanley Black & Decker, Inc.		6,993		1,045,244
				9,241,346
Media — 1.4%
Discovery, Inc., Class C(a)		71,218		1,748,402
Interpublic Group of Cos., Inc.		138,060		3,113,253
				4,861,655
Metals & Mining — 0.5%
Nucor Corp.		28,147		1,883,879
Multi-Utilities — 1.1%
Public Service Enterprise Group, Inc.		75,189		3,876,745
Multiline Retail — 0.6%
Dollar General Corp.		23,623		2,318,597
Oil, Gas & Consumable Fuels — 7.7%
Devon Energy Corp.		106,070		4,774,211
Hess Corp.		110,424		7,247,127
Marathon Oil Corp.		188,654		3,984,372
Marathon Petroleum Corp.		53,650		4,336,529
Valero Energy Corp.		19,274		2,281,078
Williams Cos., Inc.		169,789		5,051,223
				27,674,540
Personal Products — 0.6%
Nu Skin Enterprises, Inc., Class A		30,022		2,187,103

Security	Shares		Value
Pharmaceuticals — 0.7%
Mylan NV(a)		71,313	$	2,660,688
Professional Services — 1.7%
Experian PLC		122,702		3,012,603
Nielsen Holdings PLC		134,195		3,161,634
				6,174,237
Real Estate Management & Development — 0.5%
Realogy Holdings Corp.		87,627		1,916,402
Road & Rail — 0.6%
Norfolk Southern Corp.		13,155		2,223,195
Semiconductors & Semiconductor Equipment — 0.4%
Xilinx, Inc.		19,587		1,411,635
Software — 2.2%
Constellation Software, Inc.		6,681		4,843,282
Dell Technologies, Inc., Class V(a)		35,196		3,256,334
				8,099,616
Specialty Retail — 0.9%
Signet Jewelers Ltd.		15,772		910,675
Williams-Sonoma, Inc.		38,067		2,226,539
				3,137,214
Technology Hardware, Storage & Peripherals — 1.3%
HP, Inc.		82,305		1,899,599
NetApp, Inc.		38,095		2,953,125
				4,852,724
Wireless Telecommunication Services — 1.9%
Telephone & Data Systems, Inc.		270,543		6,831,211
Total Long-Term Investments — 97.9% (Cost — $325,510,699)				353,927,503
Short-Term Securities — 2.4%
BlackRock Liquidity Funds, T-Fund, Institutional Class, 1.79%(b)(c)		8,537,424		8,537,424
Total Short-Term Securities — 2.4% (Cost — $8,537,424)				8,537,424
Total Investments — 100.3% (Cost — $334,048,123)				362,464,927
Liabilities in Excess of Other Assets — (0.3)%				(1,150,178	)
Net Assets — 100.0%			$	361,314,749

^(a)  Non-income producing security.

^(b)  Annualized 7-day yield as of period end.

^(c)  During the period ended July 31, 2018, investments in issuers considered to be affiliates of the Fund for purposes of Section 2(a)(3) of the Investment Company Act of 1940, as amended, were as follows:

Affiliate	Shares Held at 01/31/18		Net Activity			Shares Held at 07/31/18		Value at 07/31/18		Income			Net Realized Gain (Loss) (a)		Change in Unrealized Appreciation (Depreciation)
BlackRock Liquidity Funds, T-Fund, Institutional Class		4,085,305		4,452,119			8,537,424	$	8,537,424	$	43,069		$	—	$	—
SL Liquidity Series, LLC, Money Market Series		11,540,038		(11,540,038	)		—		—		9,656	(b)		731		(839	)
								$	8,537,424	$	52,725		$	731	$	(839	)

^(a)  Includes net capital gain distributions, if applicable.

^(b)  Represents securities lending income earned from the reinvestment of cash collateral from loaned securities, net of fees and collateral investment expenses, and other payments to and from borrowers of securities.

For Fund compliance purposes, the Fund’s industry classifications refer to one or more of the industry sub-classifications used by one or more widely recognized market indexes or rating group indexes, and/or as defined by the investment adviser. These definitions may not apply for purposes of this report, which may combine such industry sub-classifications for reporting ease.

8 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Schedule of Investments  (unaudited) (continued) July 31, 2018 BlackRock Mid Cap Dividend Fund

Fair Value Hierarchy as of Period End

Various inputs are used in determining the fair value of investments. For information about the Fund’s policy regarding valuation of investments, refer to the Notes to Financial Statements.

The following table summarizes the Fund’s investments categorized in the disclosure hierarchy:

	Level 1		Level 2		Level 3		Total
Assets:
Investments:
Common Stocks:
Auto Components	$	2,979,383	$	—	$	—	$	2,979,383
Automobiles		1,581,882		—		—		1,581,882
Banks		35,023,675		—		—		35,023,675
Beverages		484,858		—		—		484,858
Building Products		6,326,203		—		—		6,326,203
Capital Markets		2,483,406		—		—		2,483,406
Chemicals		9,810,862		—		—		9,810,862
Commercial Services & Supplies		1,957,332		—		—		1,957,332
Communications Equipment		2,826,169		884,723		—		3,710,892
Construction Materials		—		2,387,243		—		2,387,243
Containers & Packaging		7,646,995		—		—		7,646,995
Diversified Consumer Services		1,702,175		—		—		1,702,175
Diversified Financial Services		5,943,507		—		—		5,943,507
Diversified Telecommunication Services		1,571,183		—		—		1,571,183
Electric Utilities		25,896,663		—		—		25,896,663
Electrical Equipment		3,461,101		—		—		3,461,101
Electronic Equipment, Instruments & Components		18,851,275		—		—		18,851,275
Energy Equipment & Services		2,752,624		—		—		2,752,624
Equity Real Estate Investment Trusts (REITs)		22,458,631		—		—		22,458,631
Food & Staples Retailing		2,172,361		—		—		2,172,361
Food Products		8,289,040		—		—		8,289,040
Health Care Equipment & Supplies		9,681,058		5,646,096		—		15,327,154
Health Care Providers & Services		20,034,061		—		—		20,034,061
Household Durables		4,794,937		—		—		4,794,937
Household Products		3,235,899		—		—		3,235,899
IT Services		7,100,445		—		—		7,100,445
Independent Power and Renewable Electricity Producers		2,802,888		—		—		2,802,888
Insurance		40,260,022		—		—		40,260,022
Leisure Products		3,530,019		—		—		3,530,019
Machinery		9,241,346		—		—		9,241,346
Media		4,861,655		—		—		4,861,655
Metals & Mining		1,883,879		—		—		1,883,879
Multi-Utilities		3,876,745		—		—		3,876,745
Multiline Retail		2,318,597		—		—		2,318,597
Oil, Gas & Consumable Fuels		27,674,540		—		—		27,674,540
Personal Products		2,187,103		—		—		2,187,103
Pharmaceuticals		2,660,688		—		—		2,660,688
Professional Services		3,161,634		3,012,603		—		6,174,237
Real Estate Management & Development		1,916,402		—		—		1,916,402
Road & Rail		2,223,195		—		—		2,223,195
Semiconductors & Semiconductor Equipment		1,411,635		—		—		1,411,635
Software		8,099,616		—		—		8,099,616
Specialty Retail		3,137,214		—		—		3,137,214
Technology Hardware, Storage & Peripherals		4,852,724		—		—		4,852,724
Wireless Telecommunication Services		6,831,211		—		—		6,831,211
Short-Term Securities		8,537,424		—		—		8,537,424
	$	350,534,262	$	11,930,665	$	—	$	362,464,927

During the period ended July 31, 2018, there were no transfers between levels.

Portfolio Abbreviations

ADR — American Depositary Receipts

See notes to financial statements.

SCHEDULE OF INVESTMENTS 9

Statement of Assets and Liabilities  (unaudited) 

July 31, 2018

	BlackRock Mid Cap Dividend Fund
ASSETS
Investments at value — unaffiliated (cost — $325,510,699)	$	353,927,503
Investments at value — affiliated (cost — $8,537,424)		8,537,424
Foreign currency at value (cost — $937)		939
Receivables:
Capital shares sold		224,775
Dividends — unaffiliated		135,625
Dividends — affiliated		12,141
Investments sold		4,694
Securities lending income — affiliated		918
Deferred offering costs		20,506
Prepaid expenses		48,030
Total assets		362,912,555
LIABILITIES
Payables:
Capital shares redeemed		1,007,229
Investment advisory fees		198,262
Service and distribution fees		77,792
Offering costs		26,487
Board realignment and consolidation		11,133
Directors’ and Officer’s fees		2,654
Other affiliates		1,406
Other accrued expenses		272,843
Total liabilities		1,597,806
NET ASSETS	$	361,314,749
NET ASSETS CONSIST OF
Paid-in capital	$	326,637,732
Undistributed net investment income		214,352
Accumulated net realized gain		6,045,859
Net unrealized appreciation (depreciation)		28,416,806
NET ASSETS	$	361,314,749
Institutional — Based on net assets of $102,855,428 and 5,446,839 shares outstanding, 20 million shares authorized, $0.10 par value	$	18.88
Investor A — Based on net assets of $189,510,961 and 10,524,362 shares outstanding, 40 million shares authorized, $0.10 par value	$	18.01
Investor C — Based on net assets of $24,712,727 and 1,730,060 shares outstanding, 40 million shares authorized, $0.10 par value	$	14.28
Class K — Based on net assets of $4,084,338 and 216,292 shares outstanding, 2 billion shares authorized, $0.10 par value	$	18.88
Class R — Based on net assets of $40,151,295 and 2,578,761 shares outstanding, 40 million shares authorized, $0.10 par value	$	15.57

See notes to financial statements.

10 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Statement of Operations  (unaudited) 

Six Months Ended July 31, 2018

	BlackRock Mid Cap Dividend Fund
INVESTMENT INCOME
Dividends — unaffiliated(a)	$	4,483,035
Securities lending income — affiliated — net		9,656
Dividends — affiliated		43,069
Foreign taxes withheld		(33,850	)
Total investment income		4,501,910
EXPENSES
Investment advisory		1,184,751
Service and distribution — class specific		465,605
Transfer agent — class specific		331,074
Custodian		49,519
Professional		48,354
Accounting services		47,413
Registration		41,291
Printing		28,235
Offering Costs		20,853
Directors and Officer		9,946
Board realignment and consolidation		11,133
Miscellaneous		12,051
Total expenses		2,250,225
Less:
Fees waived and/or reimbursed by the Manager		(2,432	)
Transfer agent fees reimbursed — class specific		(222,210	)
Total expenses after fees waived and/or reimbursed		2,025,583
Net investment income		2,476,327
REALIZED AND UNREALIZED GAIN (LOSS)
Net realized gain (loss) from:
Investments — unaffiliated		8,249,910
Investments — affiliated		731
Foreign currency transactions		(795	)
		8,249,846
Net change in unrealized appreciation (depreciation) on:
Investments — unaffiliated		(9,360,298	)
Investments — affiliated		(839	)
Foreign currency translations		(658	)
		(9,361,795	)
Net realized and unrealized loss		(1,111,949	)
NET INCREASE IN NET ASSETS RESULTING FROM OPERATIONS	$	1,364,378

^(a) Includes non-recurring dividends in the amount of $599,853.

See notes to financial statements.

FINANCIAL STATEMENTS 11

Statement of Changes in Net Assets

	BlackRock Mid Cap Dividend Fund
	Six Months Ended 07/31/18 (unaudited)			Year Ended 01/31/18
INCREASE (DECREASE) IN NET ASSETS
OPERATIONS
Net investment income	$	2,476,327		$	4,676,810
Net realized gain		8,249,846			74,801,417
Net change in unrealized appreciation (depreciation)		(9,361,795	)		(37,834,267	)
Net increase in net assets resulting from operations		1,364,378			41,643,960
DISTRIBUTIONS(a)
From net investment income:
Institutional		(822,769	)		(1,793,449	)
Investor A		(1,370,072	)		(1,963,889	)
Investor C		(136,580	)		(58,641	)
Class K		(31,598	)		—
Class R		(288,998	)		(408,728	)
From net realized gain:
Institutional		(1,378,491	)		(29,990,916	)
Investor A		(2,649,765	)		(41,876,021	)
Investor C		(433,956	)		(6,964,164	)
Class K		(54,170	)		—
Class R		(649,903	)		(9,921,359	)
Decrease in net assets resulting from distributions to shareholders		(7,816,302	)		(92,977,167	)
CAPITAL SHARE TRANSACTIONS
Net decrease in net assets derived from capital share transactions		(33,027,170	)		(98,650,770	)
NET ASSETS
Total decrease in net assets		(39,479,094	)		(149,983,977	)
Beginning of period		400,793,843			550,777,820
End of period	$	361,314,749		$	400,793,843
Undistributed net investment income, end of period	$	214,352		$	388,042

^(a)  Distributions for annual periods determined in accordance with U.S. federal income tax regulations.

See notes to financial statements.

12 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Financial Highlights

(For a share outstanding throughout each period)

	BlackRock Mid Cap Dividend Fund
	Institutional
	Six Months Ended 07/31/18 (unaudited)			Year Ended January 31,
				2018			2017			2016			2015			2014
Net asset value, beginning of period	$	19.13		$	21.24		$	16.52		$	21.37		$	23.30		$	20.43
Net investment income(a)		0.15	(b)		0.25	(b)		0.15			0.17			0.19			0.17
Net realized and unrealized gain (loss)		0.00	(c)		1.70			5.69			(2.22	)		1.24			4.23
Net increase (decrease) from investment operations		0.15			1.95			5.84			(2.05	)		1.43			4.40
Distributions(d)
From net investment income		(0.15	)		(0.20	)		(0.14	)		(0.23	)		(0.17	)		(0.17	)
From net realized gain		(0.25	)		(3.86	)		(0.98	)		(2.57	)		(3.19	)		(1.36	)
Total distributions		(0.40	)		(4.06	)		(1.12	)		(2.80	)		(3.36	)		(1.53	)
Net asset value, end of period	$	18.88		$	19.13		$	21.24		$	16.52		$	21.37		$	23.30
Total Return(e)
Based on net asset value		0.84	%(f)		11.13	%		35.48	%		(10.78	)%		6.06	%		21.66	%
Ratios to Average Net Assets
Total expenses		0.95	%(g)		0.90	%		0.85	%		0.94	%		0.90	%(h)		0.86	%(h)
Total expenses after fees waived and/or reimbursed and paid indirectly		0.86	%(g)		0.86	%		0.85	%		0.94	%		0.90	%(h)		0.86	%(h)
Net investment income		1.63	%(b)(g)		1.26	%(b)		0.79	%		0.81	%		0.77	%(h)		0.73	%(h)
Supplemental Data
Net assets, end of period (000)	$	102,855		$	119,371		$	207,240		$	144,008		$	154,661		$	182,951
Portfolio turnover rate		26	%		154	%		93	%		73	%		65	%		57	%

^(a)  Based on average shares outstanding.

^(b)  Net investment income per share and ratio of net investment income to average net assets include $0.03 per share and 0.16%, respectively, for the six months ended July 31, 2018 and the year ended January 31, 2018, resulting from a special dividend.

^(c)  Amount is less than $0.005 per share.

^(d)  Distributions for annual periods determined in accordance with U.S. federal income tax regulations.

^(e)  Where applicable, assumes the reinvestment of distributions.

^(f)  Aggregate total return.

^(g)  Annualized.

^(h)  Ratios do not include expenses incurred indirectly as a result of investments in underlying funds of approximately 0.02% for the years ended January 31, 2015 and January 31, 2014.

See notes to financial statements.

FINANCIAL HIGHLIGHTS 13

Financial Highlights  (continued)

(For a share outstanding throughout each period)

	BlackRock Mid Cap Dividend Fund (continued)
	Investor A
	Six Months Ended 07/31/18 (unaudited)			Year Ended January 31,
				2018			2017			2016			2015			2014
Net asset value, beginning of period	$	18.26		$	20.46		$	15.95		$	20.71		$	22.69		$	19.94
Net investment income(a)		0.12	(b)		0.18	(b)		0.09			0.11			0.11			0.10
Net realized and unrealized gain (loss)		0.01			1.63			5.49			(2.14	)		1.20			4.12
Net increase (decrease) from investment operations		0.13			1.81			5.58			(2.03	)		1.31			4.22
Distributions(c)
From net investment income		(0.13	)		(0.16	)		(0.09	)		(0.16	)		(0.11	)		(0.11	)
From net realized gain		(0.25	)		(3.85	)		(0.98	)		(2.57	)		(3.18	)		(1.36	)
Total distributions		(0.38	)		(4.01	)		(1.07	)		(2.73	)		(3.29	)		(1.47	)
Net asset value, end of period	$	18.01		$	18.26		$	20.46		$	15.95		$	20.71		$	22.69
Total Return(d)
Based on net asset value		0.75	%(e)		10.85	%		35.08	%		(11.01	)%		5.71	%		21.27	%
Ratios to Average Net Assets
Total expenses		1.23	%(f)		1.20	%		1.15	%		1.20	%		1.18	%(g)		1.16	%(g)
Total expenses after fees waived and/or reimbursed and paid indirectly		1.11	%(f)		1.12	%		1.15	%		1.20	%		1.18	%(g)		1.16	%(g)
Net investment income		1.36	%(b)(f)		0.98	%(b)		0.49	%		0.52	%		0.48	%(g)		0.43	%(g)
Supplemental Data
Net assets, end of period (000)	$	189,511		$	209,284		$	235,578		$	197,218		$	305,516		$	314,481
Portfolio turnover rate		26	%		154	%		93	%		73	%		65	%		57	%

^(a)  Based on average shares outstanding.

^(b)  Net investment income per share and ratio of net investment income to average net assets include $0.03 per share and 0.16%, respectively, for the six months ended July 31, 2018 and the year ended January 31, 2018, resulting from a special dividend.

^(c)  Distributions for annual periods determined in accordance with U.S. federal income tax regulations.

^(d)  Where applicable, excludes the effects of any sales charges and assumes the reinvestment of distributions.

^(e)  Aggregate total return.

^(f)  Annualized.

^(g)  Ratios do not include expenses incurred indirectly as a result of investments in underlying funds of approximately 0.02% for the years ended January 31, 2015 and January 31, 2014.

See notes to financial statements.

14 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Financial Highlights  (continued)

(For a share outstanding throughout each period)

	BlackRock Mid Cap Dividend Fund (continued)
	Investor C
	Six Months Ended 07/31/18 (unaudited)			Year Ended January 31,
				2018			2017			2016			2015			2014
Net asset value, beginning of period	$	14.57		$	17.09		$	13.50		$	17.95		$	20.08		$	17.80
Net investment income (loss)(a)		0.04	(b)		0.02	(b)		(0.05	)		(0.05	)		(0.07	)		(0.08	)
Net realized and unrealized gain (loss)		(0.00	)(c)		1.31			4.62			(1.81	)		1.07			3.66
Net increase (decrease) from investment operations		0.04			1.33			4.57			(1.86	)		1.00			3.58
Distributions(d)
From net investment income		(0.08	)		(0.02	)		—			(0.04	)		—			(0.00	)(c)
From net realized gain		(0.25	)		(3.83	)		(0.98	)		(2.55	)		(3.13	)		(1.30	)
Total distributions		(0.33	)		(3.85	)		(0.98	)		(2.59	)		(3.13	)		(1.30	)
Net asset value, end of period	$	14.28		$	14.57		$	17.09		$	13.50		$	17.95		$	20.08
Total Return(e)
Based on net asset value		0.32	%(f)		10.02	%		33.97	%		(11.71	)%		4.88	%		20.26	%
Ratios to Average Net Assets
Total expenses		2.02	%(g)		1.99	%		1.95	%		2.00	%		1.99	%(h)		2.00	%(h)
Total expenses after fees waived and/or reimbursed and paid indirectly		1.86	%(g)		1.90	%		1.95	%		2.00	%		1.99	%(h)		2.00	%(h)
Net investment income (loss)		0.61	%(b)(g)		0.14	%(b)		(0.31	)%		(0.27	)%		(0.33	)%(h)		(0.41	)%(h)
Supplemental Data
Net assets, end of period (000)	$	24,713		$	26,876		$	56,247		$	47,178		$	68,488		$	72,312
Portfolio turnover rate		26	%		154	%		93	%		73	%		65	%		57	%

^(a)  Based on average shares outstanding.

^(b)  Net investment income per share and ratio of net investment income to average net assets include $0.03 per share and 0.16%, respectively, for the six months ended July 31, 2018 and the year ended January 31, 2018, resulting from a special dividend.

^(c)  Amount is greater than $(0.005) per share.

^(d)  Distributions for annual periods determined in accordance with U.S. federal income tax regulations.

^(e)  Where applicable, excludes the effects of any sales charges and assumes the reinvestment of distributions.

^(f)  Aggregate total return.

^(g)  Annualized.

^(h)  Ratios do not include expenses incurred indirectly as a result of investments in underlying funds of approximately 0.02% for the years ended January 31, 2015 and January 31, 2014.

See notes to financial statements.

FINANCIAL HIGHLIGHTS 15

Financial Highlights  (continued)

(For a share outstanding throughout each period)

	BlackRock Mid Cap Dividend Fund (continued)
	Class K
	Six Months Ended 07/31/18 (unaudited)			Period from 01/25/18(a) to 01/31/18
Net asset value, beginning of period	$	19.13		$	19.37
Net investment income(b)		0.12	(c)		0.00	(d)
Net realized and unrealized gain (loss)		0.03			(0.24	)
Net increase (decrease) from investment operations		0.15			(0.24	)
Distributions(e)
From net investment income		(0.15	)		—
From net realized gain		(0.25	)		—
Total distributions		(0.40	)		—
Net asset value, end of period	$	18.88		$	19.13
Total Return(f)
Based on net asset value		0.86	%(g)		(1.24	)%(g)
Ratios to Average Net Assets
Total expenses		0.80	%(h)		0.84	%(h)(i)
Total expenses after fees waived and/or reimbursed and paid indirectly		0.80	%(h)		0.77	%(h)
Net investment income		1.25	%(h)		0.32	%(h)
Supplemental Data
Net assets, end of period (000)	$	4,084		$	198
Portfolio turnover rate		26	%		154	%

^(a)  Commencement of operations.

^(b)  Based on average shares outstanding.

^(c)  Net investment income per share and ratio of net investment income to average net assets include $0.03 per share and 0.16%, respectively, resulting from a special dividend.

^(d)  Amount is less than $0.005 per share.

^(e)  Distributions for annual periods determined in accordance with U.S. federal income tax regulations.

^(f)  Where applicable, assumes the reinvestment of distributions.

^(g)  Aggregate total return.

^(h)  Annualized.

⁽ⁱ⁾  Audit costs were not annualized in the calculation of the expense ratio. If these expenses were annualized, the total expenses would have been 0.85%.

See notes to financial statements.

16 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Financial Highlights  (continued)

(For a share outstanding throughout each period)

	BlackRock Mid Cap Dividend Fund (continued)
	Class R
	Six Months Ended 07/31/18 (unaudited)			Year Ended January 31,
				2018			2017			2016			2015			2014
Net asset value, beginning of period	$	15.85		$	18.29		$	14.36		$	18.93		$	21.00		$	18.55
Net investment income(a)		0.08	(b)		0.11	(b)		0.03			0.04			0.04			0.02
Net realized and unrealized gain (loss)		(0.00	)(c)		1.43			4.92			(1.93	)		1.12			3.83
Net increase (decrease) from investment operations		0.08			1.54			4.95			(1.89	)		1.16			3.85
Distributions(d)
From net investment income		(0.11	)		(0.13	)		(0.04	)		(0.12	)		(0.05	)		(0.04	)
From net realized gain		(0.25	)		(3.85	)		(0.98	)		(2.56	)		(3.18	)		(1.36	)
Total distributions		(0.36	)		(3.98	)		(1.02	)		(2.68	)		(3.23	)		(1.40	)
Net asset value, end of period	$	15.57		$	15.85		$	18.29		$	14.36		$	18.93		$	21.00
Total Return(e)
Based on net asset value		0.57	%(f)		10.59	%		34.58	%		(11.26	)%		5.41	%		20.88	%
Ratios to Average Net Assets
Total expenses		1.53	%(g)		1.51	%		1.48	%		1.50	%		1.49	%(h)		1.48	%(h)
Total expenses after fees waived and paid indirectly		1.36	%(g)		1.40	%		1.48	%		1.50	%		1.49	%(h)		1.47	%(h)
Net investment income		1.11	%(b)(g)		0.70	%(b)		0.16	%		0.23	%		0.17	%(h)		0.12	%(h)
Supplemental Data
Net assets, end of period (000)	$	40,151		$	45,066		$	51,713		$	44,562		$	61,956		$	68,902
Portfolio turnover rate		26	%		154	%		93	%		73	%		65	%		57	%

^(a)  Based on average shares outstanding.

^(b)  Net investment income per share and ratio of net investment income to average net assets include $0.03 per share and 0.16%, respectively, for the six months ended July 31, 2018 and the year ended January 31, 2018, resulting from a special dividend.

^(c)  Amount is greater than $(0.005) per share.

^(d)  Distributions for annual periods determined in accordance with U.S. federal income tax regulations.

^(e)  Where applicable, assumes the reinvestment of distributions.

^(f)  Aggregate total return.

^(g)  Annualized.

^(h)  Ratios do not include expenses incurred indirectly as a result of investments in underlying funds of approximately 0.02% for the years ended January 31, 2015 and January 31, 2014.

See notes to financial statements.

FINANCIAL HIGHLIGHTS 17

Notes to Financial Statements  (unaudited)

1. ORGANIZATION

BlackRock Mid Cap Dividend Series, Inc. (the “Corporation”) is registered under the Investment Company Act of 1940, as amended (the “1940 Act”), as an open-end management investment company. The Corporation is organized as a Maryland Corporation. BlackRock Mid Cap Dividend Fund (the “Fund”) is a series of the Corporation. The Fund is classified as diversified.

The Fund offers multiple classes of shares. All classes of shares have identical voting, dividend, liquidation and other rights and are subject to the same terms and conditions except that certain classes bear expenses related to the shareholder servicing and distribution of such shares. Institutional and Class K Shares are sold without a sales charge and only to certain eligible investors. Class R Shares are sold without a sales charge and only to certain employer-sponsored retirement plans. Investor A and Investor C Shares are generally available through financial intermediaries. Each class has exclusive voting rights with respect to matters relating to its shareholder servicing and distribution expenditures.

Share Class	Initial Sales Charge	CDSC			Conversion Privilege
Institutional, Class K and Class R Shares	No		No		None
Investor A Shares	Yes		No	(a)	None
Investor C Shares	No		Yes		None

^(a)  Investor A Shares may be subject to a contingent deferred sales charge (“CDSC”) for certain redemptions where no initial sales charge was paid at the time of purchase.

The Fund, together with certain other registered investment companies advised by BlackRock Advisors, LLC (the “Manager”) or its affiliates, is included in a complex of open-end funds referred to as the Equity-Bond Complex.

2. SIGNIFICANT ACCOUNTING POLICIES

The financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”), which may require management to make estimates and assumptions that affect the reported amounts of assets and liabilities in the financial statements, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. The Fund is considered an investment company under U.S. GAAP and follows the accounting and reporting guidance applicable to investment companies. Below is a summary of significant accounting policies:

Investment Transactions and Income Recognition: For financial reporting purposes, investment transactions are recorded on the dates the transactions are entered into (the “trade dates”). Realized gains and losses on investment transactions are determined on the identified cost basis. Dividend income is recorded on the ex-dividend date. Dividends from foreign securities where the ex-dividend date may have passed are subsequently recorded when the Fund is informed of the ex-dividend date. Under the applicable foreign tax laws, a withholding tax at various rates may be imposed on capital gains, dividends and interest. Upon notification from issuers, a portion of the dividend income received from a real estate investment trust may be redesignated as a reduction of cost of the related investment and/or realized gain. Income, expenses and realized and unrealized gains and losses are allocated daily to each class based on its relative net assets.

Foreign Currency Translation: The Fund’s books and records are maintained in U.S. dollars. Securities and other assets and liabilities denominated in foreign currencies are translated into U.S. dollars using exchange rates determined as of the close of trading on the New York Stock Exchange (“NYSE”). Purchases and sales of investments are recorded at the rates of exchange prevailing on the respective dates of such transactions. Generally, when the U.S. dollar rises in value against a foreign currency, the investments denominated in that currency will lose value; the opposite effect occurs if the U.S. dollar falls in relative value.

The Fund does not isolate the portion of the results of operations arising as a result of changes in the exchange rates from the changes in the market prices of investments held or sold for financial reporting purposes. Accordingly, the effects of changes in exchange rates on investments are not segregated in the Statement of Operations from the effects of changes in market prices of those investments, but are included as a component of net realized and unrealized gain (loss) from investments. The Fund reports realized currency gains (losses) on foreign currency related transactions as components of net realized gain (loss) for financial reporting purposes, whereas such components are generally treated as ordinary income for U.S. federal income tax purposes.

Distributions: Distributions paid by the Fund are recorded on the ex-dividend date. The character and timing of distributions are determined in accordance with U.S. federal income tax regulations, which may differ from U.S. GAAP.

Offering Costs: Offering costs are amortized over a 12-month period beginning with the commencement of operations of a class of shares.

Indemnifications: In the normal course of business, the Fund enters into contracts that contain a variety of representations that provide general indemnification. The Fund’s maximum exposure under these arrangements is unknown because it involves future potential claims against the Fund, which cannot be predicted with any certainty.

Other: Expenses directly related to the Fund or its classes are charged to the Fund or the applicable class. Other operating expenses shared by several funds, including other funds managed by the Manager, are prorated among those funds on the basis of relative net assets or other appropriate methods. Expenses directly related to the Fund and other shared expenses prorated to the Fund are allocated daily to each class based on its relative net assets or other appropriate methods.

18 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Notes to Financial Statements  (unaudited) (continued)

3. INVESTMENT VALUATION AND FAIR VALUE MEASUREMENTS

Investment Valuation Policies: The Fund’s investments are valued at fair value (also referred to as “market value” within the financial statements) as of the close of trading on the NYSE (generally 4:00 p.m., Eastern time). U.S. GAAP defines fair value as the price the Fund would receive to sell an asset or pay to transfer a liability in an orderly transaction between market participants at the measurement date. The Fund determines the fair values of its financial instruments using various independent dealers or pricing services under policies approved by the Board of Directors of the Corporation (the “Board”). The BlackRock Global Valuation Methodologies Committee (the “Global Valuation Committee”) is the committee formed by management to develop global pricing policies and procedures and to oversee the pricing function for all financial instruments.

Fair Value Inputs and Methodologies: The following methods and inputs are used to establish the fair value of the Fund’s assets and liabilities:

• Equity investments traded on a recognized securities exchange are valued at the official closing price each day, if available. For equity investments traded on more than one exchange, the official closing price on the exchange where the stock is primarily traded is used. Equity investments traded on a recognized exchange for which there were no sales on that day may be valued at the last available bid (long positions) or ask (short positions) price.

Generally, trading in foreign instruments is substantially completed each day at various times prior to the close of trading on the NYSE. Occasionally, events affecting the values of such instruments may occur between the foreign market close and the close of trading on the NYSE that may not be reflected in the computation of the Fund’s net assets. Each business day, the Fund uses a pricing service to assist with the valuation of certain foreign exchange-traded equity securities and foreign exchange-traded and over-the-counter (“OTC”) options (the “Systematic Fair Value Price”). Using current market factors, the Systematic Fair Value Price is designed to value such foreign securities and foreign options at fair value as of the close of trading on the NYSE, which follows the close of the local markets.

• Investments in open-end U.S. mutual funds are valued at net asset value (“NAV”) each business day.

• The Fund values its investment in SL Liquidity Series, LLC, Money Market Series (the “Money Market Series”) at fair value, which is ordinarily based upon its pro rata ownership in the underlying fund’s net assets. The Money Market Series seeks current income consistent with maintaining liquidity and preserving capital. Although the Money Market Series is not registered under the 1940 Act, its investments may follow the parameters of investments by a money market fund that is subject to Rule 2a-7 under the 1940 Act.

If events (e.g., a company announcement, market volatility or a natural disaster) occur that are expected to materially affect the value of such investments, or in the event that the application of these methods of valuation results in a price for an investment that is deemed not to be representative of the market value of such investment, or if a price is not available, the investment will be valued by the Global Valuation Committee, or its delegate, in accordance with a policy approved by the Board as reflecting fair value (“Fair Valued Investments”). The fair valuation approaches that may be used by the Global Valuation Committee will include market approach, income approach and cost approach. Valuation techniques such as discounted cash flow, use of market comparables and matrix pricing are types of valuation approaches and are typically used in determining fair value. When determining the price for Fair Valued Investments, the Global Valuation Committee, or its delegate, seeks to determine the price that the Fund might reasonably expect to receive or pay from the current sale or purchase of that asset or liability in an arm’s-length transaction. Fair value determinations shall be based upon all available factors that the Global Valuation Committee, or its delegate, deems relevant and consistent with the principles of fair value measurement. The pricing of all Fair Valued Investments is subsequently reported to the Board or a committee thereof on a quarterly basis.

Fair Value Hierarchy: Various inputs are used in determining the fair value of investments. These inputs to valuation techniques are categorized into a fair value hierarchy consisting of three broad levels for financial statement purposes as follows:

• Level 1 — Unadjusted price quotations in active markets/exchanges for identical assets or liabilities that the Fund has the ability to access

• Level 2 — Other observable inputs (including, but not limited to, quoted prices for similar assets or liabilities in markets that are active, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the assets or liabilities (such as interest rates, yield curves, volatilities, prepayment speeds, loss severities, credit risks and default rates) or other market-corroborated inputs)

• Level 3 — Unobservable inputs based on the best information available in the circumstances, to the extent observable inputs are not available (including the Fund’s own assumptions used in determining the fair value of investments)

The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). Accordingly, the degree of judgment exercised in determining fair value is greatest for instruments categorized in Level 3. The inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, for disclosure purposes, the fair value hierarchy classification is determined based on the lowest level input that is significant to the fair value measurement in its entirety. Investments classified within Level 3 have significant unobservable inputs used by the Global Valuation Committee in determining the price for Fair Valued Investments. Level 3 investments include equity or debt issued by privately held companies or funds. There may not be a secondary market, and/or there are a limited number of investors. Level 3 investments may also be adjusted to reflect illiquidity and/or non-transferability, with the amount of such discount estimated by the Global Valuation Committee in the absence of market information.

Changes in valuation techniques may result in transfers into or out of an assigned level within the hierarchy. In accordance with the Fund’s policy, transfers between different levels of the fair value hierarchy are deemed to have occurred as of the beginning of the reporting period. The categorization of a value determined for investments is based on the pricing transparency of the investments and is not necessarily an indication of the risks associated with investing in those securities.

NOTES TO FINANCIAL STATEMENTS 19

Notes to Financial Statements  (unaudited) (continued)

4. SECURITIES AND OTHER INVESTMENTS

Securities Lending: The Fund may lend its securities to approved borrowers, such as brokers, dealers and other financial institutions. The borrower pledges and maintains with the Fund collateral consisting of cash, an irrevocable letter of credit issued by a bank, or securities issued or guaranteed by the U.S. Government. The initial collateral received by the Fund is required to have a value of at least 102% of the current value of the loaned securities for securities traded on U.S. exchanges and a value of at least 105% for all other securities. The collateral is maintained thereafter at a value equal to at least 100% of the current market value of the securities on loan. The market value of the loaned securities is determined at the close of each business day of the Fund and any additional required collateral is delivered to the Fund, or excess collateral returned by the Fund, on the next business day. During the term of the loan, the Fund is entitled to all distributions made on or in respect of the loaned securities, but does not receive interest income on securities received as collateral. Loans of securities are terminable at any time and the borrower, after notice, is required to return borrowed securities within the standard time period for settlement of securities transactions.

The market value of any securities on loan, all of which were classified as common stocks in the Fund’s Schedule of Investments, and the value of any related collateral are shown separately in the Statement of Assets and Liabilities as a component of investments at value-unaffiliated, and collateral on securities loaned at value, respectively. As of period end, any securities on loan were collateralized by cash and/or U.S. Government obligations. Cash collateral invested by the securities lending agent, BlackRock Investment Management, LLC (“BIM”), if any, is disclosed in the Schedule of Investments.

Securities lending transactions are entered into by the Fund under Master Securities Lending Agreements (each, an “MSLA”), which provide the right, in the event of default (including bankruptcy or insolvency), for the non-defaulting party to liquidate the collateral and calculate a net exposure to the defaulting party or request additional collateral. In the event that a borrower defaults, the Fund, as lender, would offset the market value of the collateral received against the market value of the securities loaned. When the value of the collateral is greater than that of the market value of the securities loaned, the lender is left with a net amount payable to the defaulting party. However, bankruptcy or insolvency laws of a particular jurisdiction may impose restrictions on or prohibitions against such a right of offset in the event of an MSLA counterparty’s bankruptcy or insolvency. Under the MSLA, absent an event of default, the borrower can resell or re-pledge the loaned securities, and the Fund can reinvest cash collateral received in connection with loaned securities. Upon an event of default, the parties’ obligations to return the securities or collateral to the other party are extinguished, and the parties can resell or re-pledge the loaned securities or the collateral received in connection with the loaned securities in order to satisfy the defaulting party’s net payment obligation for all transactions under the MSLA. The defaulting party remains liable for any deficiency.

The risks of securities lending include the risk that the borrower may not provide additional collateral when required or may not return the securities when due. To mitigate these risks, the Fund benefits from a borrower default indemnity provided by BIM. BIM’s indemnity allows for full replacement of the securities loaned if the collateral received does not cover the value on the securities loaned in the event of borrower default. The Fund could incur a loss if the value of an investment purchased with cash collateral falls below the market value of loaned securities or if the value of an investment purchased with cash collateral falls below the value of the original cash collateral received.

5. DERIVATIVE FINANCIAL INSTRUMENTS

The Fund engages in various portfolio investment strategies using derivative contracts both to increase the returns of the Fund and/or to manage its exposure to certain risks such as credit risk, equity risk, interest rate risk, foreign currency exchange rate risk, commodity price risk or other risks (e.g., inflation risk). Derivative financial instruments categorized by risk exposure are included in the Schedule of Investments. These contracts may be transacted on an exchange or OTC.

Futures Contracts: Futures contracts are purchased or sold to gain exposure to, or manage exposure to, changes in interest rates (interest rate risk), and changes in the value of equity securities (equity risk) or foreign currencies (foreign currency exchange rate risk).

Futures contracts are agreements between the Fund and a counterparty to buy or sell a specific quantity of an underlying instrument at a specified price and on a specified date. Depending on the terms of a contract, it is settled either through physical delivery of the underlying instrument on the settlement date or by payment of a cash amount on the settlement date. Upon entering into a futures contract, the Fund is required to deposit initial margin with the broker in the form of cash or securities in an amount that varies depending on a contract’s size and risk profile. The initial margin deposit must then be maintained at an established level over the life of the contract. Amount pledged, which are considered restricted, are included in cash pledged for futures on the Statement of Assets and Liabilities.

Securities deposited as initial margin are designated in the Schedule of Investments and cash deposited, if any, is shown as cash pledged for futures contracts in the Statement of Assets and Liabilities. Pursuant to the contract, the Fund agrees to receive from or pay to the broker an amount of cash equal to the daily fluctuation in market value of the contract (“variation margin”). Variation margin is recorded as unrealized appreciation (depreciation) and, if any, shown as variation margin receivable (or payable) on futures contracts in the Statement of Assets and Liabilities. When the contract is closed, a realized gain or loss is recorded in the Statement of Operations equal to the difference between the notional amount of the contract at the time it was opened and the notional amount at the time it was closed. The use of futures contracts involves the risk of an imperfect correlation in the movements in the price of futures contracts and interest, foreign currency exchange rates or underlying assets.

6. INVESTMENT ADVISORY AGREEMENT AND OTHER TRANSACTIONS WITH AFFILIATES

The PNC Financial Services Group, Inc. is the largest stockholder and an affiliate of BlackRock, Inc. (“BlackRock”) for 1940 Act purposes.

Investment Advisory: The Corporation, on behalf of the Fund, entered into an Investment Advisory Agreement with the Manager, the Fund’s investment adviser, an indirect, wholly-owned subsidiary of BlackRock, to provide investment advisory and administrative services. The Manager is responsible for the management of the Fund’s portfolio and provides the personnel, facilities, equipment and certain other services necessary to the operations of the Fund.

20 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Notes to Financial Statements  (unaudited) (continued)

For such services, the Fund pays the Manager a monthly fee at an annual rate equal to the following percentages of the average daily value of the Fund’s net assets:

Average Daily Net Assets	Investment Advisory Fee
Not exceeding $1 Billion		0.65	%
In excess of $1 Billion — but not more than $3 Billion		0.61
In excess of $3 Billion — but not more than $5 Billion		0.59
In excess of $5 Billion — but not more than $10 Billion		0.57
In excess of $10 Billion		0.55

Service and Distribution Fees: The Corporation, on behalf of the Fund, entered into a Distribution Agreement and a Distribution and Service Plan with BlackRock Investments, LLC (“BRIL”), an affiliate of the Manager. Pursuant to the Distribution and Service Plan and in accordance with Rule 12b-1 under the 1940 Act, the Fund pays BRIL ongoing service and distribution fees. The fees are accrued daily and paid monthly at annual rates based upon the average daily net assets of the relevant share class of the Fund as follows:

	Investor A			Investor C			Class R
Distribution Fee		—	%		0.75	%		0.25	%
Service Fee		0.25			0.25			0.25

BRIL and broker-dealers, pursuant to sub-agreements with BRIL, provide shareholder servicing and distribution services to the Fund. The ongoing service and/or distribution fee compensates/reimburses BRIL and each broker-dealer for providing shareholder servicing and/or distribution related services to shareholders.

For the six months ended July 31, 2018, the following table shows the class specific service and distribution fees borne directly by each share class of the Fund:

Investor A		Investor C		Class R		Total
$	240,347	$	124,021	$	101,237	$	465,605

Transfer Agent: Pursuant to written agreements, certain financial intermediaries, some of which may be affiliates, provide the Fund with sub-accounting, recordkeeping, sub-transfer agency and other administrative services with respect to sub-accounts they service. For these services, these entities receive an asset-based fee or an annual fee per shareholder account, which will vary depending on share class and/or net assets. For the six months ended July 31, 2018, the Funds did not pay any amounts to affiliates in return for these services.

The Manager maintains a call center that is responsible for providing certain shareholder services to the Fund. Shareholder services include responding to inquiries and processing subscriptions and redemptions based upon instructions from shareholders. For the six months ended July 31, 2018, the Fund reimbursed the Manager the following amounts for costs incurred in running the call center, which are included in transfer agent — class specific in the Statement of Operations:

Institutional		Investor A		Investor C		Class R		Total
$	362	$	3,563	$	1,509	$	181	$	5,615

For the six months ended July 31, 2018, the following table shows the class specific transfer agent fees borne directly by each share class of the Fund:

Institutional		Investor A		Investor C		Class R		Total
$	80,556	$	175,607	$	27,644	$	47,267	$	331,074

Other Fees: For the six months ended July 31, 2018, affiliates earned underwriting discounts, direct commissions and dealer concessions on sales of the Fund’s Investor A Shares, which totaled $3,092.

For the six months ended July 31, 2018, affiliates received CDSCs as follows:

Investor A	Investor C
$419	$280

Expense Limitations, Waivers, Reimbursements, and Recoupments: The Manager voluntarily agreed to waive its investment advisory fees by the amount of investment advisory fees the Fund pays to the Manager indirectly through its investment in affiliated money market funds (the “affiliated money market fund waiver”). The amount of waivers and/or reimbursements of fees and expenses made pursuant to the expense limitation described below will be reduced by the amount of the affiliated money market fund waiver. For the six months ended July 31, 2018, the amounts waived and/or reimbursed were $1,961.

The Manager has contractually agreed to waive its investment advisory fee with respect to any portion of the Fund’s assets invested in affiliated equity and fixed-income mutual funds and exchange-traded funds that have a contractual management fee through May 31, 2019. The contractual agreement may be terminated upon 90 days’ notice by a majority of the directors who are not “interested persons” of the Corporation, as defined in the 1940 Act (“Independent Directors”) or by a vote of a majority of the outstanding voting securities of the Fund. For the six months ended July 31, 2018, the Fund did not waive any amount in investment advisory fees pursuant to these arrangements.

For the six months ended July 31, 2018, the Fund reimbursed the Manager $2,350 for certain accounting services, which is included in accounting services in the Statement of Operations.

NOTES TO FINANCIAL STATEMENTS 21

Notes to Financial Statements  (unaudited) (continued)

With respect to the Fund, the Manager contractually agreed to waive and/or reimburse fees or expenses in order to limit expenses, excluding interest expense, dividend expense, tax expense, acquired fund fees and expenses, and certain other fund expenses, which constitute extraordinary expenses not incurred in the ordinary course of the Fund’s business (“expense limitation”). The expense limitation as a percentage of average daily net assets is as follows:

Institutional	0.85	%
Investor A	1.10
Investor C	1.85
Class K	0.80
Class R	1.35

The Manager has agreed not to reduce or discontinue these contractual expense limitations through May 31, 2019, unless approved by the Board, including a majority of the Independent Directors or by a vote of a majority of the outstanding voting securities of the Fund. For the six months ended July 31, 2018, the Manager waived and/or reimbursed $ 471, which is included in fees waived and/or reimbursed by the Manager in the Statement of Operations.

These amounts waived and/or reimbursed are shown as transfer agent fees waived and/or reimbursed — class specific, in the Statement of Operations. Class specific expense waivers and/or reimbursements are as follows:

Institutional		Investor A		Investor C		Class R		Total
$	49,148	$	117,770	$	20,191	$	35,101	$	222,210

With respect to the contractual expense limitation, if during the Fund’s fiscal year the operating expenses of a share class, that at any time during the prior two fiscal years received a waiver and/or reimbursement from the Manager, are less than the current expense limitation for that share class, the Manager is entitled to be reimbursed by such share class up to the lesser of: (a) the amount of fees waived and/or expenses reimbursed during those prior two fiscal years under the agreement and (b) an amount not to exceed either the current expense limitation of that share class or the expense limitation of the share class in effect at the time that the share class received the applicable waiver and/or reimbursement, provided that:

(1) the Fund, of which the share class is a part, has more than $50 million in assets for the fiscal year, and

(2) the Manager or an affiliate continues to serve as the Fund’s investment adviser or administrator.

This repayment applies only to the contractual expense limitation on net expenses and does not apply to the contractual investment advisory fee waiver described above or any voluntary waivers that may be in effect from time to time.

On July 31, 2018, the fund level and class specific waivers and/or reimbursements subject to possible future recoupment under the expense limitation agreement are as follows:

	Expiring 01/31/20		Expiring 01/31/21
Fund Level	$	4,996	$	471
Institutional		72,313		49,148
Investor A		169,839		117,771
Investor C		31,602		20,191
Class K		—		—
Class R		52,554		35,101

Securities Lending: The U.S. Securities and Exchange Commission (“SEC”) has issued an exemptive order which permits BIM, an affiliate of the Manager, to serve as securities lending agent for the Fund, subject to applicable conditions. As securities lending agent, BIM bears all operational costs directly related to securities lending. The Fund is responsible for expenses in connection with the investment of cash collateral received for securities on loan (the “collateral investment expenses”). The cash collateral is invested in a private investment company managed by the Manager or its affiliates. However, BIM has agreed to cap the collateral investment expenses of the private investment company to an annual rate of 0.04%. The investment adviser to the private investment company will not charge any advisory fees with respect to shares purchased by the Fund. The private investment company in which the cash collateral has been invested may, under certain circumstances, impose a liquidity fee of up to 2% of the value withdrawn or temporarily restrict withdrawals for up to 10 business days during a 90 day period, in the event that the private investment company’s weekly liquid assets fall below certain thresholds.

Securities lending income is equal to the total of income earned from the reinvestment of cash collateral, net of fees and other payments to and from borrowers of securities, and less the collateral investment expenses. The Fund retains a portion of securities lending income and remits a remaining portion to BIM as compensation for its services as securities lending agent.

Pursuant to a securities lending agreement, the Fund retains 71.5% of securities lending income, and this amount retained can never be less than 65% of the total of securities lending income plus the collateral investment expenses.

In addition, commencing the business day following the date that the aggregate securities lending income earned across the Equity-Bond Complex in a calendar year exceeds a specified threshold, the Fund, pursuant to the securities lending agreement, will retain for the remainder of that calendar year securities lending income in an

22 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Notes to Financial Statements  (unaudited) (continued)

amount equal to 75% of securities lending income, and this amount retained can never be less than 65% of the total of securities lending income plus the collateral investment expenses.

The share of securities lending income earned by the Fund is shown as securities lending income — affiliated — net in the Statement of Operations. For the six months ended July 31, 2018, the Fund paid BIM $3,715 for securities lending agent services.

Interfund Lending: In accordance with an exemptive order (the “Order”) from the SEC, the Fund may participate in a joint lending and borrowing facility for temporary purposes (the “Interfund Lending Program”), subject to compliance with the terms and conditions of the Order, and to the extent permitted by the Fund’s investment policies and restrictions. The Fund is currently permitted to borrow under the Interfund Lending Program.

A lending BlackRock fund may lend in aggregate up to 15% of its net assets, but may not lend more than 5% of its net assets to any one borrowing fund through the Interfund Lending Program. A borrowing BlackRock fund may not borrow through the Interfund Lending Program or from any other source more than 33 ¹⁄₃% of its total assets (or any lower threshold provided for by the fund’s investment restrictions). If a borrowing BlackRock fund’s total outstanding borrowings exceed 10% of its total assets, each of its outstanding interfund loans will be subject to collateralization of at least 102% of the outstanding principal value of the loan. All interfund loans are for temporary or emergency purposes and the interest rate to be charged will be the average of the highest current overnight repurchase agreement rate available to a lending fund and the bank loan rate, as calculated according to a formula established by the Board.

During the period ended July 31, 2018, the Fund did not participate in the Interfund Lending Program.

Directors and Officers: Certain directors and/or officers of the Corporation are directors and/or officers of BlackRock or its affiliates. The Fund reimburses the Manager for a portion of the compensation paid to the Corporation’s Chief Compliance Officer, which is included in Directors and Officer in the Statement of Operations.

7. PURCHASES AND SALES

For the six months ended July 31, 2018, purchases and sales of investments, excluding short-term securities, were $95,609,598 and $136,454,285 respectively.

8. INCOME TAX INFORMATION

It is the Fund’s policy to comply with the requirements of the Internal Revenue Code of 1986, as amended, applicable to regulated investment companies, and to distribute substantially all of its taxable income to its shareholders. Therefore, no U.S. federal income tax provision is required.

The Fund files U.S. federal and various state and local tax returns. No income tax returns are currently under examination. The statute of limitations on the Fund’s U.S. federal tax returns generally remains open for each of the four years ended January 31, 2018. The statutes of limitations on the Fund’s state and local tax returns may remain open for an additional year depending upon the jurisdiction.

Management has analyzed tax laws and regulations and their application to the Fund as of July 31, 2018, inclusive of the open tax return years, and does not believe that there are any uncertain tax positions that require recognition of a tax liability in the Fund’s financial statements.

As of July 31, 2018, gross unrealized appreciation and depreciation for investments based on cost for U.S. federal income tax purposes were as follows:

Tax cost	$	336,146,897
Gross unrealized appreciation		40,482,679
Gross unrealized depreciation		(14,164,649	)
Net unrealized appreciation	$	26,318,030

The Tax Cuts and Jobs Act (the “Act”) was enacted on December 22, 2017. Certain provisions of the Act were effective upon enactment with the remainder becoming effective for tax years beginning after December 31, 2017. Although the Act does not amend any provisions directly related to the qualification or taxation of regulated investment companies (“RICs”), the Act does change the taxation of entities in which some RICs invest, the tax treatment of income derived from those entities and the taxation of RIC shareholders. While management does not anticipate significant impact to the Fund or to its shareholders, there is uncertainty in the application of certain provisions in the Act. Specifically, provisions in the Act may increase the amount of or accelerate the recognition of taxable income and may limit the deductibility of certain expenses by RICs. Until full clarity around these provisions is obtained, the impact on the Fund’s financial statements, if any, cannot be fully determined.

9. BANK BORROWINGS

The Corporation, on behalf of the Fund, along with certain other funds managed by the Manager and its affiliates (“Participating Funds”), is a party to a 364-day, $2.25 billion credit agreement with a group of lenders. Under this agreement, the Fund may borrow to fund shareholder redemptions. Excluding commitments designated for certain individual funds, the Participating Funds, including the Fund, can borrow up to an aggregate commitment amount of $1.75 billion at any time outstanding, subject to asset coverage and other limitations as specified in the agreement. The credit agreement has the following terms: a fee of 0.10% per annum on unused commitment amounts and interest at a rate equal to the higher of (a) one-month LIBOR (but, in any event, not less than 0.00%) on the date the loan is made plus 0.80% per annum or (b) the Fed Funds rate (but, in any event, not less than 0.00%) in effect from time to time plus 0.80% per annum on amounts borrowed. The agreement expires in April 2019 unless extended or renewed. Prior to April 19, 2018, the aggregate commitment amount was $2.1 billion and the fee was 0.12% per annum. Participating Funds paid an upfront commitment fee of 0.02% on the total commitment amounts, in addition to administration, legal and arrangement fees, which are included in miscellaneous expenses in the Statement of Operations. These fees were allocated among such funds based upon portions of the aggregate commitment available to them and relative net assets of Participating Funds. During the six months ended July 31, 2018, the Fund did not borrow under the credit agreement.

NOTES TO FINANCIAL STATEMENTS 23

Notes to Financial Statements  (unaudited) (continued)

10. PRINCIPAL RISKS

In the normal course of business, the Fund invests in securities or other instruments and may enter into certain transactions, and such activities subject the Fund to various risks, including among others, fluctuations in the market (market risk) or failure of an issuer to meet all of its obligations. The value of securities or other instruments may also be affected by various factors, including, without limitation: (i) the general economy; (ii) the overall market as well as local, regional or global political and/or social instability; (iii) regulation, taxation or international tax treaties between various countries; or (iv) currency, interest rate and price fluctuations. The Fund’s prospectus provides details of the risks to which the Fund is subject.

The Fund may be exposed to additional risks when reinvesting cash collateral in money market funds that do not seek to maintain a stable NAV per share of $1.00, which may be subject to redemption gates or liquidity fees under certain circumstances.

Valuation Risk: The market values of equities, such as common stocks and preferred securities or equity related investments, such as futures and options, may decline due to general market conditions which are not specifically related to a particular company. They may also decline due to factors which affect a particular industry or industries. The Fund may invest in illiquid investments and may experience difficulty in selling those investments in a timely manner at the price that it believes the investments are worth. Prices may fluctuate widely over short or extended periods in response to company, market or economic news. Markets also tend to move in cycles, with periods of rising and falling prices. This volatility may cause the Fund’s NAV to experience significant increases or decreases over short periods of time. If there is a general decline in the securities and other markets, the NAV of the Fund may lose value, regardless of the individual results of the securities and other instruments in which the Fund invests.

Counterparty Credit Risk: The Fund may be exposed to counterparty credit risk, or the risk that an entity may fail to or be unable to perform on its commitments related to unsettled or open transactions. The Fund manages counterparty credit risk by entering into transactions only with counterparties that the Manager believes have the financial resources to honor their obligations and by monitoring the financial stability of those counterparties. Financial assets, which potentially expose the Fund to market, issuer and counterparty credit risks, consist principally of financial instruments and receivables due from counterparties. The extent of the Fund’s exposure to market, issuer and counterparty credit risks with respect to these financial assets is approximately their value recorded in the Statement of Assets and Liabilities, less any collateral held by the Fund.

11. CAPITAL SHARE TRANSACTIONS

Transactions in capital shares for each class were as follows:

	Six Months Ended 07/31/18						Year Ended 01/31/18 (a)
	Shares			Amount			Shares			Amount
Institutional
Shares sold		683,100		$	12,708,139			2,248,617		$	43,974,684
Shares issued to shareholders in reinvestment of distributions		82,158			1,530,072			1,414,541			24,885,670
Shares redeemed		(1,557,485	)		(28,739,354	)		(7,183,325	)		(138,709,769	)
Net decrease		(792,227	)	$	(14,501,143	)		(3,520,167	)	$	(69,849,415	)
Investor A
Shares sold and automatic conversion of shares		617,669		$	10,972,558			2,440,092		$	47,030,708
Shares issued to shareholders in reinvestment of distributions		218,554			3,884,964			2,503,006			41,990,002
Shares redeemed		(1,771,071	)		(31,405,564	)		(4,998,630	)		(92,728,185	)
Net decrease		(934,848	)	$	(16,548,042	)		(55,532	)	$	(3,707,475	)
Investor C
Shares sold		69,794		$	987,281			352,356		$	5,397,503
Shares issued to shareholders in reinvestment of distributions		39,407			556,904			516,135			6,881,957
Shares redeemed		(223,531	)		(3,157,975	)		(2,315,381	)		(36,695,450	)
Net decrease		(114,330	)	$	(1,613,790	)		(1,446,890	)	$	(24,415,990	)
Class K
Shares sold		218,658		$	3,978,497			10,325		$	200,000
Shares issued to shareholders in reinvestment of distributions		4,282			79,734			—			—
Shares redeemed		(16,973	)		(315,116	)		—			—
Net increase		205,967		$	3,743,115			10,325		$	200,000
Class R
Shares sold		164,483		$	2,523,904			565,419		$	9,471,652
Shares issued to shareholders in reinvestment of distributions		61,020			938,691			708,860			10,327,803
Shares redeemed		(490,638	)		(7,569,905	)		(1,257,974	)		(20,677,345	)
Net decrease		(265,135	)	$	(4,107,310	)		16,305		$	(877,890	)
Total Net Decrease		(1,900,573	)	$	(33,027,170	)		(4,995,959	)	$	(98,650,770	)

^(a)  Period January 25, 2018 (commencement of operations) to January 31, 2018 for Class K Shares.

24 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Notes to Financial Statements  (unaudited) (continued)

As of July 31, 2018, BlackRock Financial Management, Inc., an affiliate of the Fund, owned 10,376 Class K Shares of the Fund.

12. SUBSEQUENT EVENTS

Management has evaluated the impact of all subsequent events on the Fund through the date the financial statements were issued and has determined that there were no subsequent events requiring adjustment or additional disclosure in the financial statements.

NOTES TO FINANCIAL STATEMENTS 25

Disclosure of Investment Advisory Agreement

The Board of Directors (the “Board,” the members of which are referred to as “Board Members”) of BlackRock Mid Cap Dividend Series, Inc. (the “Company”) met in person on April 10, 2018 (the “April Meeting”) and May 8, 2018 (the “May Meeting”) to consider the approval of the investment advisory agreement (the “Advisory Agreement” or the “Agreement”) between the Company, on behalf of BlackRock Mid Cap Dividend Fund (the “Fund”), and BlackRock Advisors, LLC (the “Manager” or “BlackRock”), the Fund’s investment advisor.

Activities and Composition of the Board

On the date of the May Meeting, the Board consisted of eleven individuals, nine of whom were not “interested persons” of the Company as defined in the Investment Company Act of 1940, as amended (the “1940 Act”) (the “Independent Board Members”). The Board Members are responsible for the oversight of the operations of the Fund and perform the various duties imposed on the directors of investment companies by the 1940 Act. The Independent Board Members have retained independent legal counsel to assist them in connection with their duties. The Chair of the Board is an Independent Board Member. The Board has established five standing committees: an Audit Committee, a Governance and Nominating Committee, a Compliance Committee, a Performance Oversight Committee and an Executive Committee, each of which is chaired by an Independent Board Member and composed of Independent Board Members (except for the Performance Oversight Committee and the Executive Committee, each of which also has one interested Board Member).

The Agreement

Pursuant to the 1940 Act, the Board is required to consider the continuation of the Agreement on an annual basis. The Board has four quarterly meetings per year, each typically extending for two days, and additional in-person and telephonic meetings throughout the year, as needed. The Board also has a fifth one-day meeting to consider specific information surrounding the consideration of renewing the Agreement. The Board’s consideration of the Agreement is a year-long deliberative process, during which the Board assessed, among other things, the nature, extent and quality of the services provided to the Fund by BlackRock, BlackRock’s personnel and affiliates, including (as applicable): investment management; accounting, administrative and shareholder services; oversight of the Fund’s service providers; marketing and promotional services; risk management and oversight; legal and compliance services; and ability to meet applicable legal and regulatory requirements.

The Board, acting directly and through its committees, considers at each of its meetings, and from time to time as appropriate, factors that are relevant to its annual consideration of the renewal of the Agreement, including the services and support provided by BlackRock to the Fund and its shareholders. BlackRock also furnished additional information to the Board in response to specific questions from the Board. This additional information is discussed further below in the section titled “Board Considerations in Approving the Agreement.” Among the matters the Board considered were: (a) investment performance for one-year, three-year, five-year, ten-year, and/or since inception periods, as applicable, against peer funds, applicable benchmark, and performance metrics, as applicable, as well as senior management’s and portfolio managers’ analysis of the reasons for any over-performance or underperformance relative to its peers, benchmarks, and other performance metrics, as applicable; (b) fees, including advisory, administration, if applicable, and other amounts paid to BlackRock and its affiliates by the Fund for services; (c) Fund operating expenses and how BlackRock allocates expenses to the Fund; (d) the resources devoted to, risk oversight of, and compliance reports relating to, implementation of the Fund’s investment objective(s), policies and restrictions, and meeting regulatory requirements; (e) the Fund’s adherence to its compliance policies and procedures; (f) the nature, character and scope of non-investment management services provided by BlackRock and its affiliates and the estimated cost of such services; (g) BlackRock’s and other service providers’ internal controls and risk and compliance oversight mechanisms; (h) BlackRock’s implementation of the proxy voting policies approved by the Board; (i) the use of brokerage commissions and execution quality of portfolio transactions; (j) BlackRock’s implementation of the Fund’s valuation and liquidity procedures; (k) an analysis of management fees for products with similar investment mandates across the open-end fund, exchange-traded fund (“ETF”), closed-end fund, sub-advised mutual fund, separately managed account, collective investment trust, and institutional separate account product channels, as applicable, and the similarities and differences between these products and the services provided as compared to the Fund; (l) BlackRock’s compensation methodology for its investment professionals and the incentives and accountability it creates, along with investment professionals’ investments in the fund(s) they manage; and (m) periodic updates on BlackRock’s business.

Board Considerations in Approving the Agreement

The Approval Process: Prior to the April Meeting, the Board requested and received materials specifically relating to the Agreement. The Board is continuously engaged in a process with its independent legal counsel and BlackRock to review the nature and scope of the information provided to better assist its deliberations. The materials provided in connection with the April Meeting included, among other things: (a) information independently compiled and prepared by Broadridge Financial Solutions, Inc. (“Broadridge”), based on either a Lipper classification or Morningstar category, regarding the Fund’s fees and expenses as compared with a peer group of funds as determined by Broadridge (“Expense Peers”), the investment performance of the Fund as compared with a peer group of funds (“Performance Peers”) and other metrics, as applicable; (b) information on the composition of the Expense Peers and Performance Peers, and a description of Broadridge’s methodology; (c) information on the estimated profits realized by BlackRock and its affiliates pursuant to the Agreement and a discussion of fall-out benefits to BlackRock and its affiliates; (d) a general analysis provided by BlackRock concerning investment management fees received in connection with other types of investment products, such as institutional accounts, sub-advised mutual funds, ETFs, closed-end funds, open-end funds, and separately managed accounts, under similar investment mandates, as well as the performance of such other products, as applicable; (e) review of non-management fees; (f) the existence and impact of potential economies of scale, if any, and the sharing of potential economies of scale with the Fund; (g) a summary of aggregate amounts paid by the Fund to BlackRock; (h) sales and redemption data regarding the Fund’s shares; and (i) various additional information requested by the Board as appropriate regarding BlackRock’s and the Fund’s operations.

At the April Meeting, the Board reviewed materials relating to its consideration of the Agreement. As a result of the discussions that occurred during the April Meeting, and as a culmination of the Board’s year-long deliberative process, the Board presented BlackRock with questions and requests for additional information. BlackRock responded to these requests with additional written information in advance of the May Meeting.

At the May Meeting, the Board considered, among other things: (a) the nature, extent and quality of the services provided by BlackRock; (b) the investment performance of the Fund as compared with Performance Peers and other metrics, as applicable; (c) the advisory fee and the estimated cost of the services and estimated profits realized

26 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Disclosure of Investment Advisory Agreement  (continued)

by BlackRock and its affiliates from their relationship with the Fund; (d) the Fund’s fees and expenses compared to Expense Peers; (e) the sharing of potential economies of scale; (f) fall-out benefits to BlackRock and its affiliates as a result of BlackRock’s relationship with the Fund; and (g) other factors deemed relevant by the Board Members.

The Board also considered other matters it deemed important to the approval process, such as other payments made to BlackRock or its affiliates, securities lending and cash management, services related to the valuation and pricing of Fund portfolio holdings, and advice from independent legal counsel with respect to the review process and materials submitted for the Board’s review. The Board noted the willingness of BlackRock personnel to engage in open, candid discussions with the Board. The Board did not identify any particular information as determinative, and each Board Member may have attributed different weights to the various items considered.

A. Nature, Extent and Quality of the Services Provided by BlackRock: The Board, including the Independent Board Members, reviewed the nature, extent and quality of services provided by BlackRock, including the investment advisory services and the resulting performance of the Fund. Throughout the year, the Board compared Fund performance to the performance of a comparable group of mutual funds, a relevant benchmark, and performance metrics, as applicable. The Board met with BlackRock’s senior management personnel responsible for investment activities, including the senior investment officers. The Board also reviewed the materials provided by the Fund’s portfolio management team discussing the Fund’s performance and the Fund’s investment objective(s), strategies and outlook.

The Board considered, among other factors, with respect to BlackRock: the number, education and experience of investment personnel generally and the Fund’s portfolio management team; BlackRock’s research capabilities; investments by portfolio managers in the funds they manage; portfolio trading capabilities; use of technology; commitment to compliance; credit analysis capabilities; risk analysis and oversight capabilities; and the approach to training and retaining portfolio managers and other research, advisory and management personnel. The Board also considered BlackRock’s overall risk management program, including the continued efforts of BlackRock and its affiliates to address cybersecurity risks and the role of BlackRock’s Risk & Quantitative Analysis Group. The Board engaged in a review of BlackRock’s compensation structure with respect to the Fund’s portfolio management team and BlackRock’s ability to attract and retain high-quality talent and create performance incentives.

In addition to investment advisory services, the Board considered the quality of the administrative and other non-investment advisory services provided to the Fund. BlackRock and its affiliates provide the Fund with certain administrative, shareholder and other services (in addition to any such services provided to the Fund by third parties) and officers and other personnel as are necessary for the operations of the Fund. In particular, BlackRock and its affiliates provide the Fund with administrative services including, among others: (i) responsibility for disclosure documents, such as the prospectus, the summary prospectus (as applicable), the statement of additional information and periodic shareholder reports; (ii) oversight of daily accounting and pricing; (iii) responsibility for periodic filings with regulators; (iv) overseeing and coordinating the activities of other service providers including, among others, the Fund’s custodian, fund accountant, transfer agent, and auditor; (v) organizing Board meetings and preparing the materials for such Board meetings; (vi) providing legal and compliance support; (vii) furnishing analytical and other support to assist the Board in its consideration of strategic issues such as the merger, consolidation or repurposing of certain open-end funds; and (viii) performing administrative functions necessary for the operation of the Fund, such as tax reporting, expense management, fulfilling regulatory filing requirements, overseeing the Fund’s distribution partners, and shareholder call center and other services. The Board reviewed the structure and duties of BlackRock’s fund administration, shareholder services, and legal & compliance departments and considered BlackRock’s policies and procedures for assuring compliance with applicable laws and regulations.

B. The Investment Performance of the Fund and BlackRock: The Board, including the Independent Board Members, also reviewed and considered the performance history of the Fund. In preparation for the April Meeting, the Board was provided with reports independently prepared by Broadridge, which included a comprehensive analysis of the Fund’s performance as of December 31, 2017. Broadridge ranks funds in quartiles, ranging from first to fourth, where first is the most desirable quartile position and fourth is the least desirable. In connection with its review, the Board received and reviewed information regarding the investment performance of the Fund as compared to its Performance Peers. The Board and its Performance Oversight Committee regularly review, and meet with Fund management to discuss, the performance of the Fund throughout the year.

In evaluating performance, the Board recognized that the performance data reflects a snapshot of a period as of a particular date and that selecting a different performance period could produce significantly different results. Further, the Board recognized that it is possible that long-term performance can be impacted by even one period of significant outperformance or underperformance, so that a single investment theme has the ability to affect long-term performance disproportionately.

The Board noted that for the one-, three- and five-year periods reported, the Fund ranked in the fourth, third and third quartiles, respectively, against its Performance Peers. The Board and BlackRock reviewed the Fund’s underperformance during these the applicable periods.

The Board and BlackRock discussed BlackRock’s strategy for improving the Fund’s investment performance. Discussions covered topics such as performance attribution, the Fund’s investment personnel, and the resources appropriate to support the Fund’s investment processes. The Board noted that effective June 12, 2017, the Fund had undergone changes in its investment strategy and portfolio management team, and in connection with such changes, the Fund changed its name from BlackRock Mid Cap Value Opportunities Fund to BlackRock Mid Cap Dividend Fund. The Board noted that as of March 31, 2018 the Fund is performing ahead of its benchmark since the inception of the new portfolio management team.

C. Consideration of the Advisory/Management Fees and the Estimated Cost of the Services and Estimated Profits Realized by BlackRock and its Affiliates from their Relationship with the Fund: The Board, including the Independent Board Members, reviewed the Fund’s contractual management fee rate compared with those of its Expense Peers. The contractual management fee rate represents a combination of the advisory fee and any administrative fees, before taking into account any reimbursements or fee waivers. The Board also compared the Fund’s total expense ratio, as well as its actual management fee rate, to those of its Expense Peers. The total expense ratio represents a fund’s total net operating expenses, including any 12b-1 or non 12b-1 service fees. The total expense ratio gives effect to any expense reimbursements or fee waivers that benefit a fund, and the actual management fee rate gives effect to any management fee reimbursements or waivers that benefit a fund. The Board considered the services provided and the fees charged by BlackRock and its affiliates to other types of clients with similar investment mandates, as applicable, including institutional accounts and sub-advised mutual funds (including mutual funds sponsored by third parties).

DISCLOSURE OF INVESTMENT ADVISORY AGREEMENT 27

Disclosure of Investment Advisory Agreement  (continued)

The Board received and reviewed statements relating to BlackRock’s financial condition. The Board reviewed BlackRock’s profitability methodology and was also provided with an estimated profitability analysis that detailed the revenues earned and the expenses incurred by BlackRock for services provided to the Fund. The Board reviewed BlackRock’s estimated profitability with respect to the Fund and other funds the Board currently oversees for the year ended December 31, 2017 compared to available aggregate estimated profitability data provided for the prior two years. The Board reviewed BlackRock’s estimated profitability with respect to certain other U.S. fund complexes managed by the Manager and/or its affiliates. The Board reviewed BlackRock’s assumptions and methodology of allocating expenses in the estimated profitability analysis, noting the inherent limitations in allocating costs among various advisory products. The Board recognized that profitability may be affected by numerous factors including, among other things, fee waivers and expense reimbursements by the Manager, the types of funds managed, precision of expense allocations and business mix. As a result, calculating and comparing profitability at individual fund levels is difficult.

The Board noted that, in general, individual fund or product line profitability of other advisors is not publicly available. The Board reviewed BlackRock’s overall operating margin, in general, compared to that of certain other publicly-traded asset management firms. The Board considered the differences between BlackRock and these other firms, including the contribution of technology at BlackRock, BlackRock’s expense management, and the relative product mix.

In addition, the Board considered the estimated cost of the services provided to the Fund by BlackRock, and BlackRock’s and its affiliates’ estimated profits relating to the management and distribution of the Fund and the other funds advised by BlackRock and its affiliates. As part of its analysis, the Board reviewed BlackRock’s methodology in allocating its costs of managing the Fund, to the Fund. The Board considered whether BlackRock has the financial resources necessary to attract and retain high quality investment management personnel to perform its obligations under the Agreement and to continue to provide the high quality of services that is expected by the Board. The Board further considered factors including but not limited to BlackRock’s commitment of time, assumption of risk, and liability profile in servicing the Fund in contrast to what is required of BlackRock with respect to other products with similar investment mandates across the open-end fund, ETF, closed-end fund, sub-advised mutual fund, separately managed account, collective investment trust, and institutional separate account product channels, as applicable.

The Board noted that the Fund’s contractual management fee rate ranked in the second quartile, and that the actual management fee rate and total expense ratio each ranked in the second quartile, relative to the Fund’s Expense Peers. The Board also noted that the Fund has an advisory fee arrangement that includes breakpoints that adjust the fee rate downward as the size of the Fund increases above certain contractually specified levels. In addition, the Board noted that, in connection with the changes to the Fund’s investment strategy, BlackRock proposed, and the Board agreed to, a contractual expense cap on the Fund’s total expenses as a percentage of the Fund’s average daily net assets on a class-by-class basis. This contractual expense cap was implemented on June 12, 2017.

D. Economies of Scale: The Board, including the Independent Board Members, considered the extent to which economies of scale might be realized as the assets of the Fund increase, including the existence of fee waivers and/or expense caps, as applicable, noting that any contractual fee waivers and expense caps had been approved by the Board. The Board also considered the extent to which the Fund benefits from such economies in a variety of ways, and whether there should be changes in the advisory fee rate or breakpoint structure in order to enable the Fund to more fully participate in these economies of scale. The Board considered the Fund’s asset levels and whether the current fee schedule was appropriate. In its consideration, the Board Members took into account the existence of any expense caps and further considered the continuation and/or implementation, as applicable, of such caps.

E. Other Factors Deemed Relevant by the Board Members: The Board, including the Independent Board Members, also took into account other ancillary or “fall-out” benefits that BlackRock or its affiliates may derive from BlackRock’s respective relationships with the Fund, both tangible and intangible, such as BlackRock’s ability to leverage its investment professionals who manage other portfolios and risk management personnel, an increase in BlackRock’s profile in the investment advisory community, and the engagement of BlackRock’s affiliates as service providers to the Fund, including for administrative, distribution, securities lending and cash management services. The Board also considered BlackRock’s overall operations and its efforts to expand the scale of, and improve the quality of, its operations. The Board also noted that, subject to applicable law, BlackRock may use and benefit from third party research obtained by soft dollars generated by certain registered fund transactions to assist in managing all or a number of its other client accounts.

In connection with its consideration of the Agreement, the Board also received information regarding BlackRock’s brokerage and soft dollar practices. The Board received reports from BlackRock which included information on brokerage commissions and trade execution practices throughout the year.

The Board noted the competitive nature of the open-end fund marketplace, and that shareholders are able to redeem their Fund shares if they believe that the Fund’s fees and expenses are too high or if they are dissatisfied with the performance of the Fund.

Conclusion

The Board, including the Independent Board Members, approved the continuation of the Advisory Agreement between the Manager and the Company, on behalf of the Fund, for a one-year term ending June 30, 2019. Based upon its evaluation of all of the aforementioned factors in their totality, as well as other information, the Board, including the Independent Board Members, was satisfied that the terms of the Agreement were fair and reasonable and in the best interest of the Fund and its shareholders. In arriving at its decision to approve the Agreement, the Board did not identify any single factor or group of factors as all-important or controlling, but considered all factors together, and different Board Members may have attributed different weights to the various factors considered. The Independent Board Members were also assisted by the advice of independent legal counsel in making this determination.

28 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Director and Officer Information

Robert M. Hernandez, Chair of the Board and Director

James H. Bodurtha, Director

Bruce R. Bond, Director

Honorable Stuart E. Eizenstat, Director

Henry Gabbay, Director

Lena G. Goldberg, Director

Henry R. Keizer, Director

John F. O'Brien, Director

Donald C. Opatrny, Director

Robert Fairbairn, Director

John M. Perlowski, Director, President and Chief Executive Officer

Jennifer McGovern, Vice President

Neal J. Andrews, Chief Financial Officer

Jay M. Fife, Treasurer

Charles Park, Chief Compliance Officer

John MacKessy, Anti-Money Laundering Compliance Officer

Benjamin Archibald, Secretary

Effective May 8, 2018, John MacKessy replaced Fernanda Piedra as the Anti-Money Laundering Compliance Officer of the Fund.

Investment Adviser

BlackRock Advisors, LLC

Wilmington, DE 19809

Custodian and Accounting Agent

State Street Bank and Trust Company

Boston, MA 02111

Transfer Agent

BNY Mellon Investment Servicing (US) Inc.

Wilmington, DE 19809

Distributor

BlackRock Investments, LLC

New York, NY 10022

Independent Registered Public Accounting Firm

Deloitte & Touche LLP

Boston, MA 02116

Legal Counsel

Willkie Farr & Gallagher LLP

New York, NY 10019

Address of the Corporation

100 Bellevue Parkway

Wilmington, DE 19809

DIRECTOR AND OFFICER INFORMATION 29

Additional Information

General Information

Householding

The Fund will mail only one copy of shareholder documents, including prospectuses, annual and semi-annual reports and proxy statements, to shareholders with multiple accounts at the same address. This practice is commonly called “householding” and is intended to reduce expenses and eliminate duplicate mailings of shareholder documents. Mailings of your shareholder documents may be householded indefinitely unless you instruct us otherwise. If you do not want the mailing of these documents to be combined with those for other members of your household, please call the Fund at (800) 441-7762.

Availability of Quarterly Schedule of Investments

The Fund files its complete schedule of portfolio holdings with the SEC for the first and third quarters of each fiscal year on Form N-Q. The Fund’s Forms N-Q are available on the SEC’s website at http://www.sec.gov and may also be reviewed and copied at the SEC’s Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room or how to access documents on the SEC’s website without charge may be obtained by calling (800) SEC-0330. The Fund’s Forms N-Q may also be obtained upon request and without charge by calling (800) 441-7762.

Availability of Proxy Voting Policies and Procedures

A description of the policies and procedures that the Fund uses to determine how to vote proxies relating to portfolio securities is available upon request and without charge (1) by calling (800) 441-7762; (2) at http://www.blackrock.com; and (3) on the SEC’s website at http://www.sec.gov.

Availability of Proxy Voting Record

Information about how the Fund voted proxies relating to securities held in the Fund’s portfolio during the most recent 12-month period ended June 30 is available upon request and without charge (1) at http://www.blackrock.com; or by calling (800) 441-7762 and (2) on the SEC’s website at http://www.sec.gov.

BlackRock’s Mutual Fund Family

BlackRock offers a diverse lineup of open-end mutual funds crossing all investment styles and managed by experts in equity, fixed income and tax-exempt investing. Visit http://www.blackrock.com for more information.

Shareholder Privileges

Account Information

Call us at (800) 441-7762 from 8:00 AM to 6:00 PM ET on any business day to get information about your account balances, recent transactions and share prices. You can also reach us on the Web at http://www.blackrock.com.

Automatic Investment Plans

Investor Class shareholders who want to invest regularly can arrange to have $50 or more automatically deducted from their checking or savings account and invested in any of the BlackRock funds.

Systematic Withdrawal Plans

Investor Class shareholders can establish a systematic withdrawal plan and receive periodic payments of $50 or more from their BlackRock funds, as long as their account balance is at least $10,000.

Retirement Plans

Shareholders may make investments in conjunction with Traditional, Rollover, Roth, Coverdell, Simple IRAs, SEP IRAs and 403(b) Plans.

30 2018 BLACKROCK SEMI-ANNUAL REPORT TO SHAREHOLDERS

Additional Information  (continued)

BlackRock Privacy Principles

BlackRock is committed to maintaining the privacy of its current and former fund investors and individual clients (collectively, “Clients”) and to safeguarding their non-public personal information. The following information is provided to help you understand what personal information BlackRock collects, how we protect that information and why in certain cases we share such information with select parties.

If you are located in a jurisdiction where specific laws, rules or regulations require BlackRock to provide you with additional or different privacy-related rights beyond what is set forth below, then BlackRock will comply with those specific laws, rules or regulations.

BlackRock obtains or verifies personal non-public information from and about you from different sources, including the following: (i) information we receive from you or, if applicable, your financial intermediary, on applications, forms or other documents; (ii) information about your transactions with us, our affiliates, or others; (iii) information we receive from a consumer reporting agency; and (iv) from visits to our websites.

BlackRock does not sell or disclose to non-affiliated third parties any non-public personal information about its Clients, except as permitted by law or as is necessary to respond to regulatory requests or to service Client accounts. These non-affiliated third parties are required to protect the confidentiality and security of this information and to use it only for its intended purpose.

We may share information with our affiliates to service your account or to provide you with information about other BlackRock products or services that may be of interest to you. In addition, BlackRock restricts access to non-public personal information about its Clients to those BlackRock employees with a legitimate business need for the information. BlackRock maintains physical, electronic and procedural safeguards that are designed to protect the non-public personal information of its Clients, including procedures relating to the proper storage and disposal of such information.

ADDITIONAL INFORMATION 31

This report is intended for current holders. It is not authorized for use as an offer of sale or a solicitation of an offer to buy shares of the Fund unless preceded or accompanied by the Fund’s current prospectus. Past performance results shown in this report should not be considered a representation of future performance. Investment returns and principal value of shares will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Statements and other information herein are as dated and are subject to change.

MIDCAPVAL-7/18-SAR

Item 2 – Code of Ethics – Not Applicable to this semi-annual report

Item 3 – Audit Committee Financial Expert – Not Applicable to this semi-annual report

Item 4 – Principal Accountant Fees and Services – Not Applicable to this semi-annual report

Item 5 – Audit Committee of Listed Registrants – Not Applicable

Item 6 – Investments

(a) The registrant’s Schedule of Investments is included as part of the Report to Stockholders filed under Item 1 of this Form.

(b) Not Applicable due to no such divestments during the semi-annual period covered since the previous Form N-CSR filing.

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 been no material changes to these procedures.

Item 11 – Controls and Procedures

(a) The registrant’s principal executive and principal financial officers, or persons performing similar functions, have concluded that the registrant’s disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940, as amended (the “1940 Act”)) are effective as of a date within 90 days of the filing of this report based on the evaluation of these controls and procedures required by Rule 30a-3(b) under the 1940 Act and Rule 15d-15(b) under the Securities Exchange Act of 1934, as amended.

(b) There were no changes in the registrant’s internal control over financial reporting (as defined in Rule 30a-3(d) under the 1940 Act) that occurred during the second fiscal quarter of the period covered by this report that have materially affected, or are reasonably likely to materially affect, the registrant’s internal control over financial reporting.

Item 12 – Disclosure of Securities Lending Activities for Closed-End Management Investment Companies – Not Applicable

Item 13 – Exhibits attached hereto

(a)(1) – Code of Ethics – Not Applicable to this semi-annual report

(a)(2) – Certifications – Attached hereto

(a)(3) – Not Applicable

(b) –  Certifications – Attached hereto

2

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.

	BlackRock Mid Cap Dividend Fund of BlackRock Mid Cap Dividend Series, Inc.
By:	/s/ John M. Perlowski
	John M. Perlowski
	Chief Executive Officer (principal executive officer) of
	BlackRock Mid Cap Dividend Fund of BlackRock Mid Cap Dividend Series, Inc.

Date: October 4, 2018

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:	/s/ John M. Perlowski
	John M. Perlowski
	Chief Executive Officer (principal executive officer) of
	BlackRock Mid Cap Dividend Fund of BlackRock Mid Cap Dividend Series, Inc.

Date: October 4, 2018

By:	/s/ Neal J. Andrews
	Neal J. Andrews
	Chief Financial Officer (principal financial officer) of
	BlackRock Mid Cap Dividend Fund of BlackRock Mid Cap Dividend Series, Inc.

Date: October 4, 2018

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