Group therapy is a psychological treatment method in which a trained leader guides group member interactions to provide a therapeutic experience. Irvin Yalom, a pioneer in the field, proposed that the group should serve as a “microcosm” of the larger world, in which group members gain awareness of their relational patterns and practice new, healthy behaviors. As such, group therapy may be an especially helpful setting for people to discuss a diverse range of topics, including gender identity and sexual orientation. This entry examines sexual orientation dynamics in group therapy, focusing on two group types: (1) homogeneous groups, in which all of the members identify as lesbian, gay, or bisexual (LGB), and (2) heterogeneous groups, in which LGB members are mixed with heterosexual members.