United in the belief that civilians should not suff er from intentional infl iction of widespread and systematic violence and the assumption that special measures are necessary to prevent and protect groups from such violence, a diverse group of scholars, educators, journalists, activists, advocates, policymakers, diplomats, and military leaders have raised their voices against genocide and mass atrocities. Th is group has grown exponentially over the last decade and can be understood as an emerging field in its own right. Th is essay explores some of the conceptual and practical challenges facing this field as it furthers its professional development.