For nearly sixteen years in Afghanistan, the U.S. Agency for International Development (USAID) has sought to deliver effective development results in a war zone. Its most extensive program since Vietnam, the effort has pushed the agency well beyond its traditional boundary of delivering development aid. This report—which is based on field experience in Afghanistan, interviews, and a review of retrospective analyses—examines the challenges of working amid conflict while, despite generous funding, subject to shifting political and security objectives and high expectations. Its recommendations are specific and targeted to future endeavors in similar environments around the world.