According to some theorising, in collectivistic societies, forgiveness is mainly enacted to maintain relationships, not engender emotional transformation. This present study was designed to explore whether forgiveness affects decisional and emotional forgiveness in Indonesia, a country categorised as collectivistic. The evidence‐based REACH Forgiveness psychoeducational group intervention was adapted to collectivistic culture (REACH forgiveness collectivistic; REACH‐FC), and its efficacy was assessed in a randomised controlled trial. Undergraduates in Indonesia (N = 97; 24 male; 73 female; ages 16–21) were randomly assigned within a 2 × 3(S) quasi‐experimental repeated‐measures design comparing immediate treatment (IT) and waiting list (WL) conditions [Condition (IT, WL) × Time ([S] 3 time points). Harmonious value, a personality variable assessing the strength of participants’ desire for group harmony, was the covariate. The condition × time (S) interactions for both decisional and emotional forgiveness were significant, challenging some previous literature. Clearly, not all forms of collectivism have similar effects when individuals and communities deal with transgressions.