Preventing and responding to conflict-related sexual violence (CRSV) is an international priority. The UK Government has committed to advancing this goal, primarily through its policy commitments to the Women, Peace and Security (WPS) agenda. Since the fourth UK National Action Plan (NAP) on WPS, policy has been co-owned with the Ministry of Defence, yet there is to date little research on how militaries can engage on CRSV outside of UN peacekeeping missions. This report addresses this gap and presents findings on opportunities and challenges for Defence engagement. The first section reviews past and present UK practice, drawing out existing strengths and limitations with regard to training, doctrine, human resourcing and the utility of the current human security framework. The second section surveys good practice from other contexts to identify possible lessons for UK Defence through four stages of preparation and protection work (prevention, pre-emption, response, and analysis and consolidation) as well as in cross-cutting concerns over training and staffing. The third section deals with risks and limitations, focusing on the Do No Harm principle, variation in mandates, and abuses by partner forces. The final section briefly concludes and provides ten recommendations for action.