Using an intuitively valid model example of leaderless group formation, certain hypotheses emerge about the motives and intrapsychic processes which cause leaderless group formation. These hypotheses are: (1) leaderless group formation is an attempt to resolve reciprocally a guilt-shame conflict in the individual members through equalization; (2) the principal intrapsychic mechanism used is reciprocal proxy evocation; and this secondarily results in mutual superego externalization and the collective mobilization of other defensive manoeuvres. Investigation of four leaderless groups described in the psychoanalytic and psychiatric literature bore out these hypotheses. At least three instances showed a tendency to inhibition of intellectual and reality ego functions of and communication among the members in an effort to support the group formations, their purposes and processes.