This chapter discusses the stages and processes by which insanity came to be seen first as a medical problem and then as a matter for specialized expertise. In the second half of the nineteenth century, mental disorders gained a commanding social presence due to the perceived threat of the asylum population, the profusion of nervous disorders, and their linkage to a range of polarized issues. During the twentieth-century, Freud's conception of the unconscious referred to a realm of primitive, even carnal, desires that followed its own irrational inner logic of wish fulfillment. One of the striking developments of the postwar-years in the conceptualization of mental disorders has been the influence of the social sciences, especially sociology and anthropology. Diagnostic and Statistical Manual, Mental Disorders, reflected the extension of the Kraepelin and Freudian systems, augmented by new theories of personality. Psychiatry as a learned discipline contains no one school of thought that is sufficiently-dominant to control the medical meaning of insanity.