The U.S. Environmental Protection Agency's (EPA's) Air and Energy Engineering Research Laboratory (AEERL) began a research program in 1990 with the goal of improving global landfill methane (CHb4s) emissions estimates. Part of this program is afield study to gather information that can be used to develop an empirical model of CHb4s emissions. The field study is the subject of this report. Twenty-one U.S. landfills with gas recovery systems were included in the study. Site-specific information includes average CHb4s recovery rate, landfill size, tons of refuse (refuse mass), average age of the refuse, and the climate. A correlation analysis showed that refuse mass was positively linearly correlated with landfill depth, volume, area, and well depth. Regression of the CHb4s recover rate on depth, refuse mass, and volume was significant, but depth was the best predictive variable (Rp2s = 0.53). Refuse mas was nearly as good (Rp2s = 0.50). None of the climate variables--precipitation, average temperature, dewpoint--were correlated with the CHb4s recovery rate or with CHb4s recovery per metric ton (Mg) of refuse. A large amount of the variability in CHb4s recovery remains unexplained, and is likely due to between-site differences in landfill construction, operation, and refuse composition. A model for global landfill emissions estimation is proposed.