Peace operations are a highly resilient international institution for managing armed conflict. Their resilience derives from what constructivists in International Relations theory call collective intentionality and the malleable constitutive rules that define and structure such missions. Despite a range of current constraints, challenges, and crises, peace operations are unlikely to become extinct unless a critical mass of states consistently withdraw material support for them and explicitly denigrate the concept of peace operations itself. We see little evidence that both these things are likely to occur. However, the constitutive rules guiding peace operations are likely to continue to evolve due to ideational and material changes. While the proliferation of actors and mission types makes precise predictions impossible, we expect an evolution both in how various actors define their own peace operations and how these actors relate to each other. KEYWORDS Peacekeeping; peace operations; United Nations; constructivism Peace operations involve the expeditionary use of military personnel to: help prevent armed conflict by supporting a peace process; observe or assist in the implementation of ceasefires or peace agreements; and/or enforce ceasefires, peace agreements or the will of the United Nations (UN) Security Council in order to build stable peace (Williams & Bellamy, 2021, p. 1). Since the late 1940s, peace operations have been authorized by various international organizations-most frequently the UN-and states, usually in response to war or the threat of war. They have been deployed right across the conflict cycle, including in the midst of active armed conflicts, after ceasefires, following peace agreements, and, rarely, before the outbreak of war. Peacekeepers have been variously mandated to prevent war, observe ceasefires and demilitarized zones, assist in implementing peace agreements, protect civilians, as well as stabilize and even administer war-torn territories. Occasionally, they