Although self-help groups are recognized as an important part of the continuum of services in the mental health system, confusion about what constitutes a self-help group remains. The authors outline seven criteria for defining the self-help group and differentiating it from other types of groups, such as advocacy or support groups. Self-help groups are distinguished by their supportive and educational aims, focus on a single life-disrupting event, primary purpose of supporting personal change, anonymous and confidential nature, voluntary membership, member leadership, and absence of a profit orientation. Eight basic principles underlying successful self-help groups are discussed, including the shared experience of members, their acceptance of responsibility for themselves, and their commitment to personal change.