This article examines the effect of UN actions on the duration of international crises. Four different types of action – assurance, diplomatic engagement, military involvement, and intimidation – and three different outcomes – compromise, victory, and stalemate – are considered. After building on the existing literature to develop expectations of how a third party like the UN shapes crisis trajectories, hypotheses are tested using the International Crisis Behavior (ICB) data and a new events dataset on UN activity. Results from competing-risks models reveal that UN military involvement does well to decrease the risk of one side achieving victory, and diplomatic engagement increases the ability of the belligerents to reach a compromise in the long run. Moreover, diplomatic engagement accompanied by military involvement substantially hastens the pace of stalemate outcomes. Both tactics, however, have some trade-offs. Military involvement can decrease the sense of urgency for compromise; diplomatic engagement can be used for insincere motives and increase the risk of one-sided victory over time. UN actions of assurance and simple intimidation have considerable shortcomings as crisis management vehicles.