The purpose of this paper is to provide a summary of the US activity regarding the development of biodiesel specifications and to provide an update of the latest status and activity in the US.An ASTM Biodiesel Task Force was formed in 1994 to develop a US standard for biodiesel. Several iterations of the standard have occurred between biodiesel producers, engine manufacturers, and researchers and good agreement has been reached. The National Biodiesel Board and US biodiesel suppliers have adopted specifications based on the ASTM work. Recent approval was granted for the development of a provisional ASTM biodiesel standard which would be published by ASTM while additional data and approvals for a full ASTM standard (further field data test method precision and bias information and approval of the GC method for free and total glycerine) are occurring.Background - Biodiesel, a renewable diesel fuel substitute or blending stock, is currently being commercialized in the US. Public interest in a cleaner environment and reduced dependence on foreign oil has recently given rise to several pieces of nation wide legislation and government sponsored initiatives. The most important has been the passage of the Clean Air Act Amendments of 1990 and the Energy Policy Act of 1992. Embedded in this legislation are a variety of programs encouraging the use of clean burning fuel sources and the development of domestic alternatives to petroleum based fuels. As a result, interest in a variety of alternative fuels has increased dramatically over the fast five years.During this same period, American soybean farmers also became interested in alternative uses for soybean oil due to a carry over of excess soybean oil in the market each year, a reduction in US government export support for soybean oil, and the signing of what some farmers consider restrictive international trade agreements (such as GATT). The culmination of these independent factors has spurred on the interest in biodiesel in the US and the formation of the National Biodiesel Board, a trade association dedicated to the research and commercialization of biodiesel.