There are many ways we can empower ourselves, and those around us, to live more sustainably. Psychology, the study of human behavior, offers many insights. The purpose of this handbook is to introduce you to research-based tips from psychology to help you in your personal, community, and workplace efforts to empower sustainability. The recommendations are based on empirical research; most of the studies described here have been published in peer-reviewed academic journals. This document represents many years of psychological studies. Psychology is a diverse field with many contributions to make. I have summarized the studies and findings most relevant to sustainability and sustainable behavior change.