USAID’s field guide on preventing mass atrocities is designed to provide field staff with practical guidance on a range of issues related to preventing and responding to mass atrocities. This guide unpacks critical issues for USAID officers—especially those working in high-risk environments—and provides relevant background, guidance on good practices, and illustrative programming examples. The guide also identifies other resources and offices within USAID and beyond, where field officers can seek support and more information. The guidance presented in this publication is set on a foundation established by many years of research and experience gleaned by scholars and practitioners in the fields of conflict prevention, human rights, humanitarian protection, and transitional justice. Readers who are steeped in USAID’s policies and technical resources on these subjects will find much in this document quite familiar. Indeed, USAID’s role in helping prevent mass atrocities is neither wholly new nor completely distinct. This document seeks to bring together the best thinking from closely related domains, complemented by discussion of issues that require specialized thinking from an atrocity prevention perspective.