Critical incidents (CI) have increased over the last several decades, with police officers experiencing more trauma and a rise in psychological problems. Stress inoculation training (SIT) could possibly lower symptoms of posttraumatic stress experienced by the police officers who have responded to CIs. To date, little research exists specific to using SIT to lower symptomatic effects of CIs in police officers. The purpose of this quantitative ex post facto study was to examine and compare symptoms of posttraumatic stress, depression, and anxiety for police officers who have or have not received SIT prior to a CI. The theoretical foundation was Selye's general adaptation system, a 3-stage response to a stressor: alarm reaction, resistance, and exhaustion. Survey data from a convenience sample of 85 police officers were collected using a demographic survey and the Posttraumatic Stress Disorder Checklist--Civilian version. A Cronbach's Alpha test and a multivariate analysis of variance were used to determine whether SIT has affected anxiety and depression. According to study findings, police officers who received SIT showed no statistical significance for anxiety and depression compared to police officers who did not receive SIT. This study promotes positive social change by contributing knowledge and awareness to the law enforcement field who may find these results important to consider when planning training courses for their personnel.