--- - |2- Abstract Some religious or spiritual (R/S) clients seek psychotherapy that integrates R/S values, while others may be reticent to disclose R/S‐related aspects of struggles in a presumably secular setting. We meta‐analyzed 97 outcome studies (N = 7,181) examining the efficacy of tailoring treatment to patients’ R/S beliefs and values. We compared the effectiveness of R/S‐tailored psychotherapy with no‐treatment controls, alternate secular treatments, and additive secular treatments. R/S‐adapted psychotherapy resulted in greater improvement in clients’ psychological (g = 0.74, p < 0.000) and spiritual (g = 0.74, p < 0.000) functioning compared with no treatment and non R/S psychotherapies (psychological: g = 0.33, p < 0.001; spiritual: g = 0.43, p < 0.001). In more rigorous additive studies, R/S‐accommodated psychotherapies were equally effective to standard approaches in reducing psychological distress (g = 0.13, p = 0.258), but resulted in greater spiritual well‐being (g = 0.34, p < 0.000). We feature several clinical examples and conclude with evidence‐based therapeutic practices. - Journal of Clinical Psychology, EarlyView.