Robert Greenstein is founder and executive director of the Center on Budget and Policy Priorities (CBPP), a Washington, DC think tank that focuses on federal and state fiscal policy and public programs that affect low- and moderate-income families and individuals. According to his CBPP bio, Greenstein is "an expert on the federal budget and in particular, the impact of tax and budget proposals on low-income people".
Greenstein was awarded a MacArthur Fellowship in 1996. In 1994, he was appointed by President Bill Clinton to serve on the Bipartisan Commission on Entitlement and Tax Reform. Prior to founding the Center, Greenstein was Administrator of the Food and Nutrition Service at the United States Department of Agriculture under President Jimmy Carter.