Over the past century and more, research and development (R&D) has contributed to a transformation of the U.S. food and agricultural sectors. R&D has fueled productivity growth, enabling U.S. farmers to do more with less. It has helped U.S. farmers to remain competitive in increasingly integrated global commodity markets and better achieve an environmentally sustainable supply of biofuels, fiber, and feed, as well as safe, nutritious, and affordable food. But support for U.S. public agricultural R&D has waned at a time when U.S. farm productivity growth is slowing. In what follows we describe the evolving patterns of support for public agricultural and food R&D, the shifting emphasis of spending within the broad portfolio, and some potential policy approaches to revitalize U.S. agricultural research.