NORTHERN INSTITUTIONAL FUNDS

Equity Index Portfolio

Summary Prospectus   |   April 1, 2010 Ticker: Class A—BEIAX, Class C—BEICX, Class D—BEIDX

Before you invest, you may want to review the Portfolio’s complete Prospectus, which contains more information about the Portfolio and its risks. You can find the Portfolio’s complete Prospectus and other information about the Portfolio online at www.northernfunds.com/institutional/prospectus. You can also get this information at no cost by calling 800-637-1380 or by sending an e-mail request to northern-funds@ntrs.com. If you purchase shares of the Portfolio through a financial intermediary (such as a bank or a broker-dealer), the complete Prospectus and other information are also available from your financial intermediary. The Portfolio’s complete Prospectus and Statement of Additional Information, both dated April 1, 2010, as supplemented, are incorporated by reference into this summary prospectus and may be obtained, free of charge, at the website, phone number or e-mail address noted above.

INVESTMENT OBJECTIVE

The Portfolio seeks to provide investment results approximating the aggregate price and dividend performance of the securities included in the Standard & Poor’s 500^® Composite Stock Price Index (“S&P 500 Index”).

FEES AND EXPENSES OF THE PORTFOLIO

This table describes the fees and expenses that you may pay if you buy and hold shares of the Portfolio.

Shareholder Fees (fees paid directly from your investment)
None
Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class C	Class D
Management Fees	0.10%	0.10%	0.10%
Distribution (12b-1) Fees	None	None	None
Other Expenses	0.15%	0.39%	0.54%
Administration Fees	0.10%	0.10%	0.10%
Service Agent Fees	None	0.15%	0.25%
Other Operating Expenses	0.05%	0.14%	0.19%
Total Annual Portfolio Operating Expenses	0.25%	0.49%	0.64%
Fee Waiver and/or Expense Reimbursement(1)	(0.04)%	(0.04)%	(0.04)%
Total Annual Portfolio Operating Expenses After Fee Waiver and/or Expense Reimbursement	0.21%	0.45%	0.60%

⁽¹⁾ Northern Trust Investments, N.A. (“NTI”) has agreed to reimburse certain expenses of the Portfolio. The contractual reimbursement arrangement is expected to continue until at least April 1, 2011. After this date, NTI or the Portfolio may terminate the contractual arrangements. The Portfolio’s Board of Trustees may terminate the contractual arrangements at any time if it determines that it is in the best interest of the Portfolio and its shareholders.

EXAMPLE

The following Example is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Portfolio for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Portfolio’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

	1 Year	3 Years	5 Years	10 Years
Class A	$22	$76	$137	$314
Class C	$46	$153	$270	$612
Class D	$61	$201	$353	$795

PORTFOLIO TURNOVER. The Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Portfolio shares are held in a taxable account. These costs, which are not reflected in annual portfolio operating expenses or in the Example, affect the Portfolio’s performance. During the most recent fiscal year, the Portfolio’s portfolio turnover rate was 20.10% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

Under normal circumstances, the Portfolio will invest substantially all (and at least 80%) of its net assets in the equity securities of the companies that make up the S&P 500 Index, in weightings that approximate the relative composition of the securities contained in the S&P 500 Index, and in S&P 500 Index futures approved by the Commodity Futures Trading Commission.

The S&P 500 Index is an unmanaged index, which includes 500 companies operating across a broad spectrum of the U.S. economy, and its performance is widely considered representative of the U.S. stock market as a whole. As of December 31, 2009, the approximate market capitalization range of companies included in the S&P 500 Index was between $1.1 billion and $323.7 billion.

SUMMARY PROSPECTUS 1 EQUITY INDEX PORTFOLIO

The Portfolio is passively managed, which means it tries to duplicate the investment composition and performance of the S&P 500 Index using computer programs and statistical procedures. The investment management team will buy and sell securities in response to changes in the S&P 500 Index. Because the Portfolio will have fees and transaction expenses (while the S&P 500 Index has none), returns are likely to be below those of the S&P 500 Index.

The Investment Adviser expects that, under normal circumstances, the quarterly performance of the Portfolio, before expenses, will track the performance of the S&P 500 Index within a 0.95 correlation coefficient.

S&P does not endorse any of the securities in the S&P 500 Index. It is not a sponsor of the Portfolio and is not affiliated with the Portfolio in any way.

PRINCIPAL RISKS

MARKET RISK is the risk that the value of equity securities owned by the Portfolio may decline, at times sharply and unpredictably, because of economic changes or other events that affect individual issuers or large portions of the market.

MANAGEMENT RISK is the risk that a strategy used by the investment management team may fail to produce the intended results.

TRACKING RISK is the risk that the Portfolio’s performance may vary substantially from the performance of the benchmark index it tracks as a result of share purchases and redemptions, transaction costs, expenses and other factors.

As with any mutual fund, it is possible to lose money on an investment in the Portfolio. An investment in the Portfolio is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or Northern Trust Investments, N.A. and The Northern Trust Company.

PORTFOLIO PERFORMANCE

The bar chart and table that follow provide an indication of the risks of investing in the Portfolio by showing (A) changes in the performance of the Portfolio’s Class A Shares from year to year, and (B) how the average annual total returns of the Portfolio’s outstanding classes of shares compare to those of a broad-based securities market index.

The Portfolio’s past performance, before and after taxes, is not necessarily an indication of how the Portfolio will perform in the future.

Updated performance information for the Portfolio is available and may be obtained on the Portfolio’s Web site at www.northernfunds.com/institutional or by calling 800-637-1380.

CALENDAR YEAR TOTAL RETURN (CLASS A)*

* For the periods shown in the bar chart above, the highest quarterly return was 16.00% in the second quarter of 2009, and the lowest quarterly return was (22.02)% in the fourth quarter of 2008.

AVERAGE ANNUAL TOTAL RETURNS

(For the periods ended December 31, 2009)

	Inception Date	1-Year	5-Year	10-Year		Since Inception
Class A
Return before taxes	1/11/93	26.54%	0.29%	(1.10	)%	7.64%
Return after taxes on distributions		26.00%	(0.80)%	(2.30	)%	6.04%
Return after taxes on distributions and sale of Portfolio shares		17.55%	0.22%	(1.16	)%	6.24%
Class C return before taxes	9/28/95	26.29%	0.06%	(1.33	)%	7.43%
Class D return before taxes	9/14/94	26.03%	(0.11)%	(1.48	)%	7.29%
S&P 500® Index (reflects no deduction for fees, expenses, or taxes)		26.46%	0.42%	(0.95	)%	7.75%

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown only for Class A Shares. After-tax returns for other classes will vary.

In calculating the federal income taxes due on redemptions, capital gains taxes resulting from redemptions are subtracted from the redemption proceeds and the tax benefits from capital losses resulting from the redemption are added to the redemption proceeds. Under certain circumstances, the addition of the tax benefits from capital losses resulting from redemptions may cause the Returns After Taxes on Distributions and Sale of Portfolio Shares to be greater than the Returns After Taxes on Distributions or even the Returns Before Taxes.

MANAGEMENT

INVESTMENT ADVISER AND PORTFOLIO MANAGER. Northern Trust Investments, N.A., a subsidiary of The Northern Trust Company, serves as the investment adviser of the Portfolio. Chad M. Rakvin and Brent Reeder, both Senior Vice Presidents of Northern Trust Investments, N.A., have been managers of the Portfolio since September 2005 and November 2006, respectively.

EQUITY INDEX PORTFOLIO 2 SUMMARY PROSPECTUS

PURCHASE AND SALE OF PORTFOLIO SHARES

You may purchase Portfolio shares through your institutional account at Northern Trust (or an affiliate) or an authorized intermediary or you may open an account directly with Northern Institutional Funds (the “Trust”) with a minimum initial investment of $5 million in one or more of the Trust’s portfolios. There is no minimum for subsequent investments.

On any business day, you may sell (redeem) or exchange shares through your institutional account by contacting your Northern Trust account representative or authorized intermediary. If you purchase shares directly from the Trust, you may sell (redeem) or exchange your shares in one of the following ways:

n By Mail – Send a written request to: Northern Institutional Funds, P.O. Box 75986, Chicago, Illinois 60675-5986.

n By Telephone – Call the Northern Institutional Funds Center at 800-637-1380 for instructions.

n By Wire – Authorize wire redemptions on your New Account Application and have proceeds sent by federal wire transfer to a previously designated bank account (the minimum redemption amount by this method is $10,000).

TAX INFORMATION

The Portfolio’s distributions are generally taxable to you as ordinary income, capital gains, or a combination of the two, unless you are investing through a tax-deferred arrangement, such as a 401(k) plan or an individual retirement account.

PAYMENTS TO BROKERS-DEALERS AND OTHER FINANCIAL INTERMEDIARIES

If you purchase the Portfolio through a broker-dealer or other financial intermediary (such as a bank), the Portfolio and its related companies may pay the intermediary for the sale of Portfolio shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Portfolio over another investment. Ask your salesperson or visit your financial intermediary’s Web site for more information.

SUMMARY PROSPECTUS 3 EQUITY INDEX PORTFOLIO

EQUITY INDEX PORTFOLIO 4 SUMMARY PROSPECTUS NIF SUM EIP