Abstract: Working in public safety organizations or the military poses higher risk of occupational stress injuries. Effective psychological treatments that address these conditions are offered in both inpatient and outpatient settings. Beyond the common variables inherent in most psychological interventions (e.g., therapeutic alliance and empathy), studies have attempted to examine the unique variables within these treatments to understand the mechanism of change. Mechanisms of change studies have been primarily conducted in outpatient settings with a focus on symptom reduction excluding subjective factors like the quality of life. However, inpatient care offers opportunities for individuals to focus on recovery in a controlled environment that often provides more holistic care versus outpatient programs. We conducted a qualitative study to explore the perspective of service users receiving inpatient treatment for posttraumatic stress disorder with or without a substance use disorder at a facility designed for public safety personnel. We conducted interviews with 30 individuals during the last few weeks of treatment. We applied qualitative content analysis to interpret the participants' responses through coding and identifying themes. The results reveal factors to which participants attributed their improvements of mental health and are presented by type of intervention. This study sheds light on the multifaceted mechanisms of change that underpin successful inpatient treatment for public safety personnel. By elucidating how structured therapies, holistic programming, and recreational activities collectively contribute to recovery, these findings offer ideas that may be used to build a framework for enhancing inpatient care and addressing the unique needs of these occupational groups.