The purpose of this research project was to arrive at a better understanding of the development of posttraumatic stress disorder (PTSD) following a work-related accident by studying the associated risk and protective factors. The project originated with a request from the police, as officers are often exposed to traumatic events (TEs). The researchers worked on the hypothesis that peri- and posttraumatic factors could better explain the development of PTSD and workers’ ability to cope with TEs than pretraumatic factors. This study is original in that it focuses on little-researched protective factors, distinguishes three types of factors (pre-, peri- and posttraumatic) and concerns Quebec police officers.