Preventive diplomacy and conflict prevention are intended to stop armed conflicts before they escalate. Conflict prevention is a broader concept referring to the monitoring, containment, and reduction of risk factors that shape war onset, intensification, and spread. Both constructs were conceived in the latter half of the 20th century, which was characterised by a sizeable array of international or interstate wars. There has since been a growth in capacities to anticipate and prevent conflicts before they erupt. This report considers historical trends, emerging opportunities, and recurrent challenges associated with preventive diplomacy and conflict prevention. Recommendations for future conflict prevention activities include sharing but not aligning conflict analyses, aligning conflict analyses with local understandings and terminology, researching drivers of peace separately from drivers of violence, studying the micro-determinants of success in preventive action, beginning a dialogue on the co-ordination of preventive action, and ensuring sufficient and flexible financing for preventive action.