This chapter examines some of the relations between analytic theory and psychosis. It shows that there are considerable differences between the various theories of the unconscious, the first object of analytic study. Alongside the dynamic unconscious, whose basis is repression and the conflict between instinct and culture, Sigmund Freud described other forms of unconscious functioning. While continuing to espouse Freud’s theory of the unconscious, Melanie Klein contributed two significant innovations: the notion of unconscious fantasy and the introduction, alongside repression, of the concept of splitting of the object and, later, of splitting and projection. In Wilfred Bion, the unconscious forfeits the ontic connotation of place: it is a function of the mind and not a space for depositing the repressed. Psychosis, like neurosis, is interpreted in accordance with the theory of dreams and the revealing of unconscious contents.