Variations in techniques of group psychotherapy are related to the clients' ego strength. Clients with developmental or pathological ego deficit have different needs for social controls than those with good ego endowment. This paper illustrates differential use of such controls in three areas. 1. Constacy of the treatment milieu as a frame of reference: For patients with good ego endowment, time and place of group meetings should be kept constant to allow them to look inwards and permit experience of feelings hitherto avoided. A patient is described who, following a break-through of feelings in the group, attempted to disrupt the therapy by usurping control over time and place of sessions. Holding time and place of group meetings constant allows patients with ego deficit to anticipate events and helps them build additional controls over impulses. Responses of borderline patients to changes in the treatment milieu are described. 2. Control of group interactions: Matching group members for ego strength is considered essential. Clinical vignettes illustrate contrasts in group interactions considered therapeutic for patients with ego deficit and those with good ego endowment. Techniques for the first group include ritualising the group process, emphasis on reality rather than fantasy and dilution of inter-patient rapport; techniques that aid patients with good ego endowment to relinquish pathological controls include support of basic questions concerning the individual's identity, free flow of fantasy, tolerance of tension, silences or strong ventilation of affect and facilitating observations from patients concerning the process of interaction. 3. Relationship to the leader: For patients with developmental or pathological ego deficit, it is essential that the therapist be ready to set limits and lend defences when the patient's controls fail. Patients with good ego endowment often have too much control. It follows that the therapist will intervene, clarify and provide structure in the first group much more frequently than in groups for psychoneurotics. For patients with ego deficit the relation to the therapist may have to be moderated lest it further weaken ego boundaries. Such patients often need personal distance. Transference to the institution, to the treatment milieu and to the group as a concrete object provides these patients with a natural means of distancing relationships. The therapist should attempt to fit into this series. He should be highly visible in the benign exercise of his professional function. Rapport should be kept stable and primarily positive even after termination of treatment. In contrast, groups of patients with good ego endowment may relate to the therapist more intensively if he is less visible. These patients, unless they can move back and forth between positive and negative rapport, can hardly be said to be working. They will often attempt to control rapport with the therapist by splitting the transference...