Faced with the threat of climate change, there is a challenge to promote more environmentally friendly consumption patterns. This work seeks to unearth psychographic and socio-demographic factors that could trigger environmentally motivated reductions in consumption. The context of empirical investigation is the European Union (i.e., a large-scale sample of European citizens), with a focus on two key types of environmentally motivated consumption reduction: domestic and “out-of-home” (purchasing) activities. The findings show the interrelated effects of environmental knowledge and ecological motivations (in both aggregated and disaggregated forms) on positive and negative environmental attitudes, which in turn influence consumption reduction. There is also evidence of significant moderating influences of perceived environmental threat, gender, age, education, and country value orientation—particularly on “environmental knowledge” links. The findings reported here contribute to theory and practice toward environmental sustainability.