Spirituality is a multifaceted construct that might affect veterans’ recovery from posttraumatic stress disorder (PTSD) in adaptive and maladaptive ways. Using a cross-lagged panel design, this study examined longitudinal associations between spirituality and PTSD symptom severity among 532 U.S. veterans in a residential treatment program for combat-related PTSD. Results indicated that spirituality factors at the start of treatment were uniquely predictive of PTSD symptom severity at discharge, when accounting for combat exposure and both synchronous and autoregressive associations between the study variables, βs = .10 to .16. Specifically, veterans who scored higher on adaptive dimensions of spirituality (daily spiritual experiences, forgiveness, spiritual practices, positive religious coping, and organizational religiousness) at intake fared significantly better in this program. In addition, possible spiritual struggles (operationalized as negative religious coping) at baseline were predictive of poorer PTSD outcomes, β = .11. In contrast to these results, PTSD symptomatology at baseline did not predict any of the spirituality variables at posttreatment. In keeping with a spiritually integrative approach to treating combat-related PTSD, these results suggest that understanding the possible spiritual context of veterans’ trauma-related concerns might add prognostic value and equip clinicians to alleviate PTSD symptomatology among those veterans who possess spiritual resources or are somehow struggling in this domain.