In this paper the theory of the superego is explored from the point of view of ego psychology. It traces the historical background in Freud's original contributions and the more contemporary understanding of the forces at work in the formation of this new psychic structure as they come together at a unique point in development, the oedipal phase. Superego functions are delineated, and precursors of superego functioning are differentiated from the functioning of the superego proper. Some attention is paid to the distinctions between ego and superego identifications, and between guilt and shame. Some clinical illustrations are included.