NORTHERN MID CAP INDEX FUND

MID CAP INDEX FUND

INVESTMENT OBJECTIVE

The Fund seeks to provide investment results approximating the overall performance of the common stocks included in the Standard & Poor’s MidCap 400^® Composite Stock Price Index (“S&P MidCap 400 Index”).

FEES AND EXPENSES OF THE FUND

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

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees (USD $)	NORTHERN MID CAP INDEX FUND
Shareholder Fees (fees paid directly from your investment)	none

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

Annual Fund Operating Expenses		NORTHERN MID CAP INDEX FUND
Management Fees		0.20%
Other Expenses		0.31%
Administration Fees		0.15%
Transfer Agency Fees		0.10%
Other Operating Expenses		0.06%
Acquired Fund Fees and Expenses		0.01%
Total Annual Fund Operating Expenses	[1]	0.52%
Expense Reimbursement	[2]	(0.36%)
Total Annual Fund Operating Expenses After Expense Reimbursement	[1]	0.16%

EXAMPLE

The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund 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 Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
NORTHERN MID CAP INDEX FUND	16	130	255	618

PORTFOLIO TURNOVER.

The Fund 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 Fund shares are held in a taxable account. These costs, which are not reflected in annual portfolio operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 9.57% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGIES

Under normal circumstances, the Fund will invest substantially all (and at least 80%) of its net assets in equity securities included in the S&P MidCap 400 Index, in weightings that approximate the relative composition of securities contained in the S&P MidCap 400 Index, and in S&P MidCap 400 Index futures approved by the Commodity Futures Trading Commission.

The S&P MidCap 400 Index is a capitalization-weighted index of mid cap common stocks selected by Standard & Poor's. The companies chosen for inclusion in the S&P MidCap 400 Index tend to be industry leaders within the U.S. economy as determined by Standard & Poor's^® Ratings Services ("S&P"). However, companies are not selected by S&P for inclusion in the S&P MidCap 400 Index because they are expected to have superior stock price performance relative to the market in general or other stocks in particular. As of May 31, 2013, the market capitalization of the companies in the S&P MidCap 400 Index was between $543.1 million and $17.5 billion.

The Fund is passively managed, which means it tries to duplicate the investment composition and performance of the S&P MidCap 400 Index by using computer programs and statistical procedures. The Fund's investment adviser will buy and sell securities in response to changes in the S&P MidCap 400 Index. Because the Fund will have fees and transaction expenses (while the S&P MidCap 400 Index has none), returns are likely to be below those of the S&P MidCap 400 Index.

The Fund's investment adviser expects that, under normal circumstances, the quarterly performance of the Fund, before expenses, will track the performance of the S&P MidCap 400 Index within a 0.95 correlation coefficient.

S&P does not endorse any of the securities in the S&P MidCap 400 Index. It is not a sponsor of the Mid Cap Index Fund and is not affiliated with the Fund in any way.

PRINCIPAL RISKS

MARKET RISK is the risk that the value of equity securities owned by the Fund 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 Fund's investment adviser may fail to produce the intended results.

TRACKING RISK is the risk that the Fund'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.

MID CAP STOCK RISK is the risk that stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies. Mid-sized companies may have limited product lines or financial resources, and may be dependent upon a particular niche of the market.

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

FUND PERFORMANCE

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

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

Updated performance information for the Fund is available and may be obtained on the Fund's Web site at www.northernfunds.com or by calling 800-595-9111.

CALENDAR YEAR TOTAL RETURN*

*Year to date total return for the six months ended June 30, 2013 is 14.47%. For the periods shown in the bar chart above, the highest quarterly return was 19.90% in the third quarter of 2009, and the lowest quarterly return was (25.72)% in the fourth quarter of 2008.

AVERAGE ANNUAL TOTAL RETURN
(For the periods ended December 31, 2012)

Average Annual Total Returns	Inception Date	1-Year	5-Year	Since Inception
NORTHERN MID CAP INDEX FUND	Mar. 22, 2005	17.76%	4.85%	6.92%
NORTHERN MID CAP INDEX FUND Return after taxes on distributions		17.04%	4.35%	6.30%
NORTHERN MID CAP INDEX FUND Return after taxes on distributions and sale of Fund shares		12.24%	3.98%	5.80%
NORTHERN MID CAP INDEX FUND S&P MidCap 400® Index (reflects no deduction for fees, expenses, or taxes)		17.88%	5.15%	7.30%

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.

[1] The Total Annual Fund Operating Expenses and Total Annual Fund Operating Expenses After Expense Reimbursement will not correlate to the Fund's ratio of average net assets to (1) expenses before reimbursements and credits and (2) expenses net of reimbursements and credits, respectively, included in the Fund's Financial Highlights in the Fund's complete Prospectus, which do not reflect indirect expenses, such as Acquired Fund Fees and Expenses.

[2] Northern Trust Investments, Inc. has contractually agreed to reimburse a portion of the operating expenses of the Fund (other than acquired fund fees and expenses; a portion of the compensation paid to each Trustee who is not an officer, director or employee of Northern Trust Corporation or its subsidiaries; expenses related to third-party consultants engaged by the Board of Trustees of the Trust; membership dues paid to the Investment Company Institute and Mutual Fund Directors Forum; and extraordinary expenses and interest, if any) to the extent the "Total Annual Fund Operating Expenses" exceed 0.15%. This contractual limitation may not be terminated before July 31, 2014 without the approval of the Board of Trustees. Northern Trust Investments, Inc. serves as the investment adviser and administrator to the Fund. The Northern Trust Company, an affiliate of Northern Trust Investments, Inc., serves as transfer agent, custodian and sub-administrator to the Fund.