This report examines the obstacles that continue to hamper the integration of women into Formed Police Units (FPUs) of Peacekeeping Operations in accordance with the principles of United Nations (UN) Resolution 1325. To address this topic the study (1) briefly establishes the emerging importance of police units to peacekeeping operations, (2) outlines the key principles of UN Resolution 1325, (3) discusses the need for diversity, especially gender diversity, in police units, (4) discusses the core obstacles to integrating women into police units, (5) offers accounts of the major UN peacekeeping missions that utilized Formed Police Units (FPUs) or their predecessor organizations, and (6) concludes with summary recommendations for improving the integration of women into FPUs.