A variety of disciplines examine human-environment interactions, identifying factors that affect environmental outcomes important for human well-being. A central challenge for these disciplines is integrating an ever-increasing number of findings into a coherent body of theory. Without a repository for this theory, researchers cannot adequately leverage this knowledge to guide future empirical work. Comparability across field sites, study areas and scientific fields is hampered, as is the progress of sustainability science. To address this challenge we constructed the first repository of theoretical statements linking social and ecological variables to environmental outcomes.