OBJECTIVES: Public safety personnel (PSP) are frequently exposed to psychologically traumatic events. The exposures potentiate posttraumatic stress injuries (PTSIs), including posttraumatic stress disorder (PTSD). The Royal Canadian Mounted Police (RCMP) Protocol was designed to mitigate PTSIs using ongoing monitoring and PSP-delivered Emotional Resilience Skills Training (ERST) based on the Unified Protocol for the Transdiagnostic Treatment of Emotional Disorders. The current study pilot-tested ERST effectiveness among diverse PSP. METHODS: A 16-month longitudinal design engaged serving PSP (n = 119
34 % female
firefighters, municipal police, paramedics, public safety communicators) who completed PSP-delivered ERST. Participants were assessed for symptoms of PTSIs, including but not limited to PTSD, at pre- and post-training, and 1-year follow-up using self-report measures and clinical interviews. RESULTS: There were reductions in self-report and clinical diagnostic interview positive screens for PTSD and other PTSI from pre- to post-training (ps <
0.05), with mental health sustained or improved at 1-year follow-up. Improvements were observed among firefighters (Cohen's d = 0.40 to 0.71), police (Cohen's d = 0.28 to 0.38), paramedics (Cohen's d = 0.20 to 0.56), and communicators (Cohen's d = 0.05 to 0.14). CONCLUSION: Ongoing monitoring and PSP-delivered ERST, can produce small to large mental health improvements among diverse PSP, or mitigate PSP mental health challenges, with variations influenced by pre-training factors and organizational supports. ERST replication and extension research appears warranted. TRIAL REGISTRATION: Hypotheses Registration: aspredicted.org, #90136. Registered 7 March 2022 - Prospectively registered. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05530642.