Practitioners concerned with reducing or preventing violent interstate or inter-communal conflict need to learn lessons from history to make well-informed choices. Although expert judgment is critical in learning and applying such lessons, social scientific analysis can help practitioners diagnose conflict situations and understand the general conditions under which and the processes by which particular interventions are likely to ameliorate particular kinds of conflict situations. This article identifies numerous conceptual, methodological, and inferential challenges of using a scientific approach to evaluate the effects of past conflict resolution interventions. It also assesses possible ways of meeting each challenge. The authors conclud...