Interest in sustainable agriculture probably had its roots in the concept of sustainable development. There exist no agricultural production technologies or farming systems that are environmentally benign. The question thus becomes "what is sustainable and what is not?" The two underlying themes that appear in most definitions of sustainability and sustainable farming systems deal with (1) the economic profitability of the farming system over a long period of time; and (2) long-term benefits to the environment. To the extent that the proposed (sustainable) farming system provides greater off-site benefits than the farming system currently in place, federal, state and even local governments may have an interest in assuring that the alternative is implemented. Any regulations placed on U.S. farmers in an effort to achieve environmental goals cannot be so onerous such that U.S. farmers will no longer be able to produce commodities profitably at world market prices.