This article provides a historical perspective on how both American and European psychiatrists have conceptualized and categorized sexual deviance throughout the past 150 years. During this time, quite a number of sexual preferences, desires, and behaviors have been pathologized and depathologized at will, thus revealing psychiatry's constant struggle to distinguish mental disorder--in other words, the "perversions," "sexual deviations," or "paraphilias"--from immoral, unethical, or illegal behavior. This struggle is apparent in the works of 19th- and early-20th-century psychiatrists and sexologists, but it is also present in the more recent psychiatric textbooks and diagnostic manuals, such as the consecutive editions of the Diagnostic and Statistical Manual of Mental Disorders (DSM). While much of the historical literature revolves around the controversy over homosexuality, this article also reviews the recent medicohistorical and sociohistorical work on other forms of sexual deviance, including the diagnostic categories listed in the latest edition, the DSM-IV-TR: exhibitionism, voyeurism, fetishism, frotteurism, pedophilia, sexual masochism, sexual sadism, and transvestic fetishism.