In a group randomized trial of critical incident stress debriefing (CISD) with platoons of 952 peacekeepers, CISD was compared with a stress management class (SMC) and survey-only (SO) condition. Multilevel growth curve modeling found that CISD did not differentially hasten recovery compared to the other two conditions. For those soldiers reporting the highest degree of exposure to mission stressors, CISD was minimally associated with lower reports of posttraumatic stress and aggression (vs. SMC), higher perceived organizational support (vs. SO), and more alcohol problems than SMC and SO. Soldiers reported that they liked CISD more than the SMC, and CISD did not cause undue distress.