R/I LargeCap S&P 500 Index Summary

Before you invest, you may want to review the Fund's prospectus, which contains more information about the Fund and its risks. You can find the Fund's prospectus and other information about the Fund online at www.principalfunds.com/prospectus. You can also get this information at no cost by calling 1-800-222-5852 or by sending an email request to prospectus@principalfunds.com.

This Summary Prospectus incorporates by reference the Statutory Prospectus for Classes R-1, R-2, R-3, R-4, R-5, Institutional shares dated March 1, 2013 and the Statement of Additional Information dated March 1, 2013 (which may be obtained in the same manner as the Prospectus).



	Institutional Class	Class R-1	Class R-2	Class R-3	Class R-4	Class R-5
Management Fees	0.15%	0.15%	0.15%	0.15%	0.15%	0.15%
Distribution and/or Service (12b-1) Fees	N/A	0.35%	0.30%	0.25%	0.10%	N/A
Other Expenses	0.01%	0.54%	0.46%	0.33%	0.29%	0.27%
Total Annual Fund Operating Expenses	0.16%	1.04%	0.91%	0.73%	0.54%	0.42%

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:



	1 year		3 years		5 years		10 years
Institutional Class	$	16	$	52	$	90	$	205
Class R-1	106		331		574		1,271
Class R-2	93		290		504		1,120
Class R-3	75		233		406		906
Class R-4	55		173		302		677
Class R-5	43		135		235		530

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 fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 3.5% of the average value of its portfolio.

Under normal circumstances, the Fund invests at least 80% of its net assets, plus any borrowings for investment purposes, in equity securities of companies that compose the S&P 500 Index at the time of purchase. The Index is designed to represent U.S equities with risk/return characteristics of the large cap universe. As of December 31, 2012, the market capitalization range of the Index was between approximately $1.6 billion and $499.7 billion. The Fund employs a passive investment approach designed to attempt to track the performance of the Index. The Fund utilizes derivative strategies. Specifically, the Fund invests in index futures and options and exchange-traded funds ("ETFs") on a daily basis to gain exposure to the Index in an effort to minimize tracking error relative to the benchmark.

The Fund may be an appropriate investment for investors seeking long-term growth of capital, willing to accept the potential for volatile fluctuations in the value of investments and preferring a passive, rather than active, management style.

The value of your investment in the Fund changes with the value of the Fund's investments. Many factors affect that value, and it is possible to lose money by investing in the Fund. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks of investing in the Fund, in alphabetical order, are:

Derivatives Risk. Transactions in derivatives may increase volatility, cause the liquidation of portfolio positions when not advantageous to do so and produce disproportionate losses.

Equity Securities Risk. The value of equity securities could decline if the issuer's financial condition declines or in response to overall market and economic conditions. A fund's principal market segment(s), such as large cap, mid cap or small cap stocks, or growth or value stocks, may underperform other market segments or the equity markets as a whole. Investments in smaller companies and mid-size companies may involve greater risk and price volatility than investments in larger, more mature companies.

Exchange-Traded Funds ("ETFs") Risk. An ETF is subject to the risks associated with direct ownership of the securities comprising the index on which the ETF is based. Fund shareholders indirectly bear their proportionate share of the expenses of the ETFs in which the fund invests.

Index Fund Investment Risk. More likely than not, an index fund will not provide investment performance that matches the index performance due to cashflows and the fees and expenses of the fund.

Risk of Being an Underlying Fund. A fund is subject to the risk of being an underlying fund to the extent that a fund of funds invests in the fund. An underlying fund of a fund of funds may experience relatively large redemptions or investments as the fund of funds periodically reallocates or rebalances its assets. These transactions may cause the underlying fund to sell portfolio securities to meet such redemptions, or to invest cash from such investments, at times it would not otherwise do so, and may as a result increase transaction costs and adversely affect underlying fund performance.

The following information provides an indication of the risks of investing in the Fund. The bar chart shows the investment returns of the Fund’s Institutional Class shares for each full calendar year of operations for 10 years (or, if shorter, the life of the Fund). The table shows, for each share class of the Fund and for the last one, five, and ten calendar year periods (or, if shorter, the life of the Fund), how the Fund’s average annual total returns compare to the returns of one or more broad-based market indices. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. You may get updated performance information online at www.principal.com or by calling 1-800-222-5852.

The R-3 Class shares were first sold on December 6, 2000. The R-1 Class shares were first sold on November 1, 2004. For periods prior to the date on which the R-1 Class began operations, its returns are based on the performance of the Fund’s R-3 Class shares adjusted to reflect the fees and expenses of the R-1 Class. These adjustments result in performance (for the periods prior to the date the R-1 Class shares began operations) that is no higher than the historical performance of the R-3 Class shares.



Highest return for a quarter during the period of the bar chart above:	Q2 '09	15.80	%
Lowest return for a quarter during the period of the bar chart above:	Q4 '08	-22.11	%



Average Annual Total Returns
For the periods ended December 31, 2012	1 Year	5 Years	10 Years
Institutional Class Return Before Taxes	15.73%	1.48%	6.88%
Institutional Class Return After Taxes on Distributions	15.39%	1.18%	6.47%
Institutional Class Return After Taxes on Distribution and Sale of Fund Shares	10.69%	1.20%	5.99%
Class R-1 Return Before Taxes	14.82%	0.61%	5.95%
Class R-2 Return Before Taxes	14.87%	0.75%	6.10%
Class R-3 Return Before Taxes	15.10%	0.93%	6.28%
Class R-4 Return Before Taxes	15.33%	1.11%	6.50%
Class R-5 Return Before Taxes	15.51%	1.22%	6.60%
S&P 500 Index (reflects no deduction for fees, expenses, or taxes)	16.00%	1.66%	7.10%

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. The after-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Institutional Class shares only and would be different for Class R-1, R-2, R-3, R-4 and R-5 shares.

There are no restrictions on amounts to be invested in shares of the Fund for an eligible purchaser. You may purchase or redeem shares on any business day (normally any day when the New York Stock Exchange is open for regular trading) through your plan or intermediary; by sending a written request to Principal Funds at P.O. Box 8024, Boston, MA 02266-8024 (regular mail) or 30 Dan Road, Canton, MA 02021-2809 (overnight mail); calling us at 1-800-222-5852; or accessing our website (www.principalfunds.com).

The Fund’s distributions you receive are generally subject to federal income tax as ordinary income or capital gain and may also be subject to state and local taxes, unless you are tax-exempt or your account is tax-deferred in which case your distributions would be taxed when withdrawn from the tax-deferred account.

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank, insurance company, investment adviser, etc.), the Fund and its related companies may pay the intermediary for the sale of Fund 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 Fund over another investment, or to recommend one share class of the Fund over another share class. Ask your salesperson or visit your financial intermediary's website for more information.



	Class R-1	Class R-2	Class R-3	Class R-4	Class R-5	Institutional
Ticker Symbol(s)	PLPIX	PLFNX	PLFMX	PLFSX	PLFPX	PLFIX


Note:	“Standard & Poor's 500" and "S&P 500^®" are trademarks of The McGraw-Hill Companies, Inc. and have been licensed by Principal. The Fund is not sponsored, endorsed, sold, or promoted by Standard & Poor's and Standard & Poor's makes no representation regarding the advisability of investing in the Fund.


•	Thomas L. Kruchten (since 2011), Research Analyst and Portfolio Manager