Life Cycle Assessment (LCA) of transportation fuels from biomass resources is a cradle to grave evaluation of energy and environmental issues associated with producing, collecting, and transporting the biomass, converting the biomass into transportation fuels, and distributing and using the transportation fuel in motor vehicles. Biomass transportation fuel LCAs frequently include an assessment of the petroleum derived product that they will displace as a means to compare the two products. Energy and environmental issues examined include the use of crude oil, nonrenewable energy consumption, greenhouse gas emissions, compounds that form smog, compounds involved in acid rain formation, and compounds involved in the creation of dead zones in aquatic systems. The production and use of ethanol from corn grain, corn stover (the above ground non-grain portion of the corn plant), and switchgrass (a perennial prairie grass being developed for energy use) and the production and use of biodiesel from soybeans reduce crude oil use, non-renewable energy use, and greenhouse gas emissions relative to using gasoline and petroleum derived diesel fuel respectively. Impacts on compounds involved in smog formation, acid rain formation, and acquatic dead zones are mixed depending on biomass resource and biofuel produced.