The problems of solid waste management, escalating energy prices, and corresponding energy shortages and curtailments are recognized as issues of national concern as well as important management considerations for livestock and poultry producers. One way of handling both the energy and manure management problems is to implement waste disposal systems which incorporate energy conversion technologies. The systems under consideration in this study use anaerobic digestion to biologically degrade livestock and poultry manures into a fuel gas which is 60-70 percent methane (CH4). A major factor in determining the output of methane from anaerobic digestion is the physical design of the digestor. Besides reactor design, there are a number of other environmental and operational factors which affect the quantity and quality of gas production. These include amounts of volatile solids or available nutrients in the manure, temperature and pH of the slurry, retention time of the slurry, and the presence of toxic materials and oxygen. These factors can be altered by digester design and management practices and will change as learning about these systems accumulates.