In the past several years, researchers, educators, policymakers, and activists have initiated sustainable agriculture programs and efforts the world over. This development has sometimes been accompanied by a sense that it is time to stop discussing sustainability at a conceptual level and get on with the work of making agriculture sustainable. Our perspective is that it is critical to pursue a comprehensive definition of sustainability in order to set sustainable agriculture priorities and ensure that sustainable agriculture takes a path that does not reproduce problems of conventional agriculture. In this paper we briefly review some popular definitions of sustainable agriculture and find that their focus is primarily on farm-level resource conservation and profitability as the main components of sustainability. Others have challenged this approach for either not examining the social aspects of sustainability or for containing an implicit assumption that working on the environmental, production, and microeconomic aspects of sustainability will automatically take care of its social aspects. We propose an expanded conceptualization of sustainability—one that focuses on the entire food and agriculture system at a global level and includes not only environmental soundness and economic viability, but social equity as well. In this perspective, issues such as poverty and hunger are as central to achieving agricultural sustainability as those of soil erosion and adequate farm returns.