The use of biomass as an energy feedstock is emerging as a potentially viable alternative to address U.S. energy security concerns, foreign oil dependence, rural economic development, and diminishing sources of conventional energy. Biomass (organic matter that can be converted into energy) may include food crops, crops for energy, crop residues, wood waste and byproducts, and animal manure. Most legislation involving biomass has focused on encouraging the production of liquid fuels from corn. For over 30 years, the term biomass has been a part of legislation enacted by Congress for various programs, indicating some interest by the general public and policymakers in expanding its use. To aid understanding of why U.S. consumers, utility groups, refinery managers, and others have not fully adopted biomass as an energy resource, this report investigates the characterization of biomass in legislation.