Psychology can make a significant contribution to limiting the magnitude of climate change by improving understanding of human behaviors that drive climate change and human reactions to climate-related technologies and policies, and by turning that understanding into effective interventions. This article develops a framework for psychological contributions, summarizes what psychology has learned, and sets out an agenda for making additional contributions. It emphasizes that the greatest potential for contributions from psychology comes not from direct application of psychological concepts but from integrating psychological knowledge and methods with knowledge from other fields of science and technology. (Contains 1 table.)