ObjectivesThis study investigated whether training in compassion can broaden individuals’ moral circles. In total, 102 participants, including 87 females, took part in a brief seminar on Compassion Focused Therapy (CFT), which is a psychological intervention aimed at cultivating greater levels of compassion.MethodParticipants were randomized to either the CFT intervention (n = 48) or waitlist control group (n = 54). Participant levels of moral expansiveness (moral concern for human, non-human animals, and environmental entities) were measured at pre-intervention, 2 weeks post-intervention, and the CFT group again at 3-month follow-up.ResultsAt 2 weeks post-intervention, participants in the CFT group compared to control had significantly increased total moral expansiveness, as well as increases specifically for family and revered sub-groups. At 3-month follow-up, these outcomes improved, with reported moral concern for all sub-groups significantly increasing, including out-groups, stigmatized members of society, animals, plants, and the environment.ConclusionsThe results show promise for how we can expand the boundaries of our moral concern through compassion focused interventions.PreregistrationThe study was preregistered on the Open Science Framework (https://osf.io/z3c9f).