D. Yalom's (1995) hypothesis that group climate mediates the relationship between leadership and outcome was tested. Group leaders (N = 43) recorded intentions, and adolescent group members (N = 233) rated climate after 8 semistructured group sessions. Members also rated satisfaction at termination. Leader intentions comprised 4 dimensions: therapeutic work, safe environment, interpersonal, and group structure. Changing group climates did mediate between these intentions and member outcome. Therapeutic work was negatively related and safe environment was positively related to an increasingly active and engaged climate, which was related to treatment benefit. Group structure and possibly interpersonal intentions were related to a climate decreasing in conflict and distance, which was related to a positive leader relationship. The importance of leaders focusing on group process rather than individual change is highlighted.For Yalom (1995), the group leader's primary responsibility is the creation of a therapeutic group climate. "If it is the group members who, in their interaction, set in motion the many therapeutic factors, then it is the group therapist's task to create a culture maximally conducive to effective group interaction" (Yalom, pp. 109-110). Yalom's writings suggest that the group members have a direct influence on member outcome whereas the group leader's influence is indirect, acting through the creation of a therapeutic group climate, denned as a series of interactional dimensions (MacKenzie, 1983). Group climate should mediate the relationship between group leader activity and group member outcome.Viewing group climate as a mediator provides a framework for summarizing the group leadership and group climate literatures. Baron and Kenny (1986) defined a mediator as a variable that explains the relationship between a