 This article provides a comprehensive review of theory and research on individual level predictors of household energy usage. We examine two broad categories of variables that have been identified as potentially important for explaining variability in energy consumption and conservation. Theory, research and practice can be greatly advanced by understanding what these factors are, and how, when, where, why and for whom they operate. This article was authored by Alicia R. Fredericks, Karen Stenner and Elizabeth the Fifth-Hobbman.