["Journal of Traumatic Stress, EarlyView. ", "\nAbstract\nPosttraumatic stress disorder (PTSD) significantly impacts active duty service members, posing challenges to both individual well‐being and military readiness. This study examined the long‐term outcomes of a residential PTSD treatment program, focusing on the association between symptom change and military separation. Participants were 282 active duty service members diagnosed with PTSD. PTSD symptom severity was assessed weekly using the PTSD Checklist–Military version (PCL‐M). Military separation data were collected from administrative records. A multivariate joint model analyzed the association between PTSD symptoms and time to separation, whereas a Cox regression analysis explored differences across treatment response subgroups. On average, participants reported a significant 0.83‐point weekly decrease in PTSD symptom severity, B = −1.49, p < .001. The linear slope of PCL‐M scores significantly predicted separation, with each 1‐point weekly decrease in symptoms associated with a 2.4% lower risk of separation. Critically, service members classified as “improved” demonstrated a significantly lower risk of separation compared with those characterized as “worsened,” hazard ratio = 1.51, 95% CI [1.01, 2.26], p = .044. The findings highlight that PTSD symptom improvement during residential treatment is a significant predictor of military retention. This underscores the importance of effective PTSD treatment not only for improving psychological well‐being but also for contributing to force readiness.\n"]