The problem of premature termination is addressed as a pervasively critical issue in group treatment. The phenomenon of dropouts and castouts is as old as man, from the casting out of Adam and Eve. The literature on premature termination is reviewed, and its emphasis on inadequate preparation of members, feelings of alienation from the group, and the role of early provocateurs is explored. The role of the therapist in contributing to loss of members is examined in terms of insufficient understanding of members' nuclear dynamics and countertransference resistances. The vulnerability of new members to group hostility and to subsequent expulsion is recognized. The exposure of members and groups to toxic dosages of emotional stimulation is identified as a frequent dynamic in premature termination. The crucial task of the therapist in monitoring the level of such exposure is stressed. The significant role of the screening process in identifying potential dropouts is illustrated, and measures to prevent defections from the group are offered.