RESEARCH QUESTION: What is the evidence for the clinical benefit and harm of critical incident stress debriefing for first responders? [...] The intent is to provide a list of sources and a summary of the best evidence on the topic that CADTH could identify using all reasonable efforts within the time allowed. [...] SUMMARY OF FINDINGS: Two randomized controlled trials (RCTs) in US soldiers and peacekeepers were identified.8-11 No studies were indentified for the use of CISD in first-responders, such as police officers. [...] Battlemind debriefing was similar to most group psychological debriefing models, consisting of seven phases and the median duration of the 26 sessions was 50 minutes. [...] There was no evidence of change in term of distress levels immediately before and after the interventions, and no differences between groups.