A novel process has been developed and evaluated in a pilotscale program for conversion of the biodegradable fraction of municipal solid waste (MSW) to methane via anaerobic composting. The sequential batch anaerobic composting (SEBAC) process employs leachate management to provide organisms, moisture, and nutrients required for rapid conversion of MSW and removal of inhibitory fermentation products during start-up. The biodegradable organic materials are converted to methane and carbon dioxide in 21-42 d, rather than the years required in landfills.