Group therapy offers both an effective and cost-effective means to support mental health. Facilitators are key to the benefits that clients derive from group therapy. However, minimal research has examined how their effectiveness can be maximized. To address this limitation, we propose that group facilitators should be conceptualized as leaders, and that identity leadership theory provides a valuable framework for efforts to understand and increase their effectiveness. We introduce and review identity leadership theory and its evidence base, then propose three key pathways through which identity leadership can enable therapy facilitators to support improved treatment outcomes. Specifically, we argue that by engaging in identity leadership, facilitators can (a) improve clients’ attendance at therapy sessions, (b) create new, health-promoting norms and identities, and (c) foster stronger therapeutic relationships with and among group members.