Although the literature in peace psychology has been growing rapidly, many American psychologists are unaware of how conflict is resolved and peace is conceptualized and achieved. This article reviews the long history and broadening scope of peace psychology and introduces a model of peace that is useful for organizing the literature. The model suggests that peace can be facilitated at four different points of intervention. The authors discuss relationships between positive and negative peace, structural and direct violence, and peacekeeping, peacemaking, and peacebuilding. They advance some challenges for peace psychologists and conclude that peace psychology is a crucial field for grappling with humanity's most pressing problems in the coming decades. (Contains 2 figures.)