Peacebuilding programming and policy is based on assumptions about how development interventions can contribute to peace, but little research has been done to rigorously test these theories of change. On June 7, 2019, IPA Peace & Recovery Program Coordinator Nessa Kenny and J-PAL Policy Manager Aprille Knox gave a brown-bag presentation at the United States Institute of Peace (USIP0 in order to engage USIP staff in thinking about how to produce and use evidence for peace. The session, entitled "Impact evaluations in peacebuilding: The what, why, and how," explored how impact evaluations can be used by program implementers and policymakers to better understand what kinds of interventions contribute—and how they contribute—to sustainable peace. To do this, the presenters outlined how impact evaluations build the evidence base for programming, highlighted how program-implementing organizations can produce and use evidence in their work, and walked participants interactively through the process of designing, running, and learning from an impact evaluation, using the example of this evaluation in Sierra Leone