Objectives: Our objective was to determine if symptoms of depression and posttraumatic stress disorder (PTSD) are associated with peritraumatic dissociation, and if this association is modified by trauma prior to police work. Method: Symptoms of depression, PTSD symptoms, peritraumatic dissociative experience (PDE), and trauma before police work were measured using the Centre for Epidemiologic Studies Depression scale, PTSD Check List-Civilian Version, PDE questionnaire, and the brief trauma questionnaire, respectively in 328 police officers. Separate regression models were used to assess if either symptoms of depression or symptoms of PTSD were associated with PDE stratified by prior trauma. Means were adjusted for race, number of drinks per week, and smoking. Results: PDE was significantly positively associated with symptoms of PTSD and depression (b = 0.642, p = 0.0001 and b = 0.276, p = 0.0002, respectively). PDE was positively associated with symptoms of PTSD regardless of trauma before police work (b = 0.599, p < 0.0001 (without prior trauma), 0.750, p < 0.0001 (with prior trauma). In contrast to PTSD, depression symptoms were significantly associated with PDE scores in individuals with prior trauma (b = 0.466, p = 0.0001), but not in individuals without prior trauma (b = 0.130, p = 0.155). Conclusions: The results indicate that an increase in PDE is associated with an increase in symptoms of depression and PTSD. The results also show that PDE is associated with symptoms of PTSD regardless of prior trauma. In contrast, PDE was associated with depression symptoms only in individuals with prior trauma, indicating prior trauma may modify this relationship.