"Multiple personality" remains surrounded with a halo of the occult, and, as a rare exotic, fits uneasily into the framework of modern psychotherapy. Yet, the spirit-possession phenomena which it so closely resembles are widely distributed and commonly reported; and therefore, from the comparative perspective of anthropology, the truly interesting question is not why it occurs at all but why it occurs so seldom. This essay is an anthropologically motivated intellectual history of the perceived relation between multiple personality, possession, and kindred states. On the theoretical side, it concerns the creative role of psychological curing, the influence of theory upon the existence of the things which it is held to explain, and the influence of social and cultural factors on self-perception and the topography of the ego. I will begin by outlining the relation between multiple personality and possession, and follow with an account of how certain Western psychological theorists once tentatively allowed for the real existence of possession. Next I will examine cases of multiple personality in which possession was considered to play a literal role. As such an interpretation became increasingly suspect, decline of belief in possession was paralleled by a decline of interest in multiple personality as such and in the frequency of reported cases.