Environmental scientists warn that the health of the planet is rapidly deteriorating, and the primary cause of the crisis is human behavior. Psychology can contribute greatly to understanding and changing behaviors that negatively impact global ecosystems; however, environmental issues are not generally included in psychology curricula, and psychology is not often represented in environmental curricula. We describe the relevance of psychology to environmental problem solving; suggest how to integrate environmental issues into psychology courses; and urge psychology faculty to collaborate with environmental studies and science faculty to strengthen the training of future policy makers, conservation scientists, and activists. We conclude that psychology has a critical role to play in creating a sustainable society.