DELAWARE GROUP® ADVISER FUNDS

Delaware Diversified Income Fund

(the “Fund”)

Supplement to the Fund’s Class A, Class B, Class C, Class R, and Institutional Class

Statutory Prospectuses dated February 28, 2011

The following replaces the information in the section entitled “Who manages the Fund? – Investment manager”:

Who manages the Fund?

Investment manager

Delaware Management Company

Portfolio managers	Title with Delaware Management Company	Start date on the Fund
Roger A. Early, CPA, CFA, CFP	Senior Vice President, Co-Chief Investment Officer – Total Return Fixed Income Strategy	May 2007
Paul Grillo, CFA	Senior Vice President, Co-Chief Investment Officer – Total Return Fixed Income Strategy	February 2001
Wen-Dar Chen, Ph.D.	Vice President, Portfolio Manager – International Debt	May 2007
Thomas H. Chow, CFA	Senior Vice President, Senior Portfolio Manager	May 2007
Kevin P. Loome, CFA	Senior Vice President, Senior Portfolio Manager, Head of High Yield Investments	August 2007
J. David Hillmeyer, CFA	Vice President, Portfolio Manager, Head of Investment Grade Corporate Trading	February 2011

The following replaces the biographical information in the section entitled “Who manages the Fund - Portfolio managers.”

Portfolio managers

Roger A. Early, Paul Grillo, Wen-Dar Chen, Thomas H. Chow, Kevin P. Loome, and J. David Hillmeyer have primary responsibility for making day-to-day investment decisions for the Fund.

Roger A. Early, CPA, CFA, CFP, Senior Vice President, Co-Chief Investment Officer — Total Return Fixed Income Strategy

Roger A. Early rejoined Delaware Investments in March 2007 as a member of the firm’s taxable fixed income portfolio management team, with primary responsibility for portfolio construction and strategic asset allocation. During his previous time at the firm, from 1994 to 2001, he was a senior portfolio manager in the same area, and he left Delaware Investments as head of its U.S. investment grade fixed income group. In recent years, Early was a senior portfolio manager at Chartwell Investment Partners and Rittenhouse Financial and served as the chief investment officer for fixed income at Turner Investments. Prior to joining Delaware Investments in 1994, he worked for more than 10 years at Federated Investors where he managed more than $25 billion in mutual fund and institutional portfolios in the short-term and investment grade markets. He left the firm as head of institutional fixed income management. Earlier in his career, he held management positions with the Federal Reserve Bank, PNC Financial, Touche Ross, and Rockwell International. Early earned his bachelor’s degree in economics from The Wharton School of the University of Pennsylvania and an MBA with concentrations in finance and accounting from the University of Pittsburgh. He is a member of the CFA Society of Philadelphia.

Paul Grillo, CFA, Senior Vice President, Co-Chief Investment Officer — Total Return Fixed Income Strategy

Paul Grillo is a member of the firm’s taxable fixed income portfolio management team with primary responsibility for portfolio construction and strategic asset allocation. He is also a member of the firm’s asset allocation committee, which is responsible for building and managing multi-asset class portfolios.He joined Delaware Investments in 1992 as a mortgage-backed and asset-backed securities analyst, assuming portfolio management responsibilities in the mid-1990s. Grillo serves as co-lead portfolio manager for the firm’s Diversified Income products and has been influential in the growth and distribution of the firm’s multisector strategies. Prior to joining Delaware Investments, Grillo served as a mortgage strategist and trader at Dreyfus Corporation. He also worked as a mortgage strategist and portfolio manager at Chemical Investment Group and as a financial analyst at Chemical Bank. Grillo holds a bachelor’s degree in business management from North Carolina State University and an MBA with a concentration in finance from Pace University.

Wen-Dar Chen, Ph.D. , Vice President, Portfolio Manager — International Debt

Wen-Dar Chen, Ph.D., is a member of the firm’s taxable fixed income portfolio management team with primary responsibility for constructing global investment themes, international portfolio strategic asset allocation, and risk management. He has specialized in quantitative fixed income investments since 1986. Before he joined Delaware Investments in mid-2004 as a senior international debt analyst, he was a quantitative analyst in global asset-backed securities, credit strategies, and portfolio strategies at J.P. Morgan Securities. Since 1998, he has worked to promote the asset-backed securities business in Asia, and published the book, Asset-Backed Securitization – Theory and Practice, in Asia in 2002. He worked at Salomon Brothers from 1993 to 1996, and Lehman Brothers from 1990 to 1993, during which time he gained experience with government securities trading desks, proprietary trading of structured products, financial strategies, and index strategies groups. Dr. Chen’s degrees include a bachelor’s degree in atmospheric sciences from the National Taiwan University, a master’s degree in meteorology from the South Dakota School of Mines and Technology, and a Ph.D. in geophysical fluid dynamics from Princeton University.

Thomas H. Chow, CFA, Senior Vice President, Senior Portfolio Manager

Thomas H. Chow is a member of the firm's taxable fixed income portfolio management team, with primary responsibility for portfolio construction and strategic asset allocation in investment grade credit exposures. He is the lead portfolio manager for Delaware Corporate Bond Fund and Delaware Extended Duration Bond Fund, as well as several institutional mandates. His experience includes significant exposure to asset liability management strategies and credit risk opportunities. Prior to joining Delaware Investments in 2001 as a portfolio manager working on the Lincoln General Account, he was a trader of high grade and high yield securities, and was involved in the portfolio management of collateralized bond obligations (CBOs) and insurance portfolios at SunAmerica/AIG from 1997 to 2001. Before that, he was an analyst, trader, and portfolio manager at Conseco Capital Management from 1989 to 1997. Chow received a bachelor’s degree in business analysis from Indiana University, and he is a Fellow of Life Management Institute.

Kevin P. Loome, CFA, Senior Vice President, Senior Portfolio Manager, Head of High Yield Investments

Kevin P. Loome is head of the High Yield fixed income team, responsible for portfolio construction and strategic asset allocation of all high yield fixed income assets. Prior to joining Delaware Investments in August 2007 in his current position, Loome spent 11 years at T. Rowe Price, starting as an analyst and leaving the firm as a portfolio manager. He began his career with Morgan Stanley as a corporate finance analyst in the New York and London offices. Loome received his bachelor’s degree in commerce from the University of Virginia and earned an MBA from the Tuck School of Business at Dartmouth.

J. David Hillmeyer, CFA, Vice President, Portfolio Manager, Head of Investment Grade Corporate Trading

J. David Hillmeyer is a member of the firm's taxable fixed income portfolio management team, with primary responsibility for portfolio construction and asset allocation of diversified floating rate strategies. In addition, he is head of investment grade corporate trading. Prior to joining Delaware Investments in August 2007 as a vice president and corporate bond trader, he worked for more than 11 years in various roles at Hartford Investment Management Company, including senior corporate bond trader, high yield portfolio manager / trader, and quantitative analyst. He began his career as an investment advisor in January 1989 at Shawmut Bank, leaving the firm as an investment officer in November 1995. Hillmeyer earned his bachelor’s degree from Colorado State University.

The SAI provides additional information about the portfolio managers' compensation, other accounts managed by the portfolio managers, and the portfolio managers' ownership of Fund shares.

Investments in the Fund are not and will not be deposits with or liabilities of Macquarie Bank Limited ABN 46 008 583 542 and its holding companies, including their subsidiaries or related companies (the "Macquarie Group"), and are subject to investment risk, including possible delays in repayment and loss of income and capital invested. No Macquarie Group company guarantees or will guarantee the performance of the Fund, the repayment of capital from the Fund, or any particular rate of return.

Please keep this Supplement for future reference.

This Supplement is dated August 15, 2011.