Objective This study investigates the efficacy of the 6‐hour REACH Forgiveness intervention among culturally diverse undergraduates. Method Female undergraduates (N = 102) and foreign extraction (46.2%) and domestic (43.8%) students in the United States were randomly assigned to immediate treatment or waitlist conditions. Treatment efficacy and the effect of culture on treatment response were assessed using measures of emotional and decisional forgiveness across 3 time periods. Results Students in the treatment condition reported greater improvement in emotional forgiveness, but not decisional forgiveness, relative to those in the waitlist condition. Gains were maintained at a 1‐week follow‐up. Although culture did not moderate the effect of treatment, a main effect of culture on emotional forgiveness and marginally significant interaction effect of culture on decisional forgiveness were found. Conclusion The REACH Forgiveness intervention was efficacious for college students from different cultural backgrounds when conducted in the United States. However, some evidence may warrant development of culturally adapted forgiveness interventions.