Beginning in infancy, normal individuals satisfy their basic instincts and desires (e.g., self-preservation, self-development, procreative instinct) chiefly through interpersonal relations: a child's relations with its mother secure its self-preservation, spouses fulfill their procreative instinct through a mutual loving relationship. In a normal individual's psyche the ego achieves a balance between the desires of the id and the controls of the superego. The deviant personality is incapable of satisfying its desires through interpersonal relationships and within the norms of its societal group. From an etiological viewpoint, the deviant personality can be classified as influenced by psychosocial factors, by a combination of psychological and biological factors, and by biological factors entirely. Among the former are childhood psychoses (e.g., episodic epileptoid dyscontrol, enuresis, sleepwalking, nervous tics) related to the child's failure to satisfy its self-preservation instincts through positive relationships with its parents. The same symptoms in adolescence and adulthood can be linked to the failure to satisfy the procreative instinct through normal sexual relations, often resulting in sex offenses. Criminal acts can also be caused by personality deformities, manifestations of dyscontrol due to psychogenic, neuropsychological, hormonal, or biochemical factors. Organic or biological factors (e.g., hypoglycemia, hypofolliculosis) may induce destructive behavior, especially in combination with arrested sexual development. Deviants and criminals are incapable of finding the causes of their abnormal behavior in themselves, but blame societal rejection and failure of others to relate to them. Persuasion and counseling must be attempted to heal the deviant psyche. Deviants and delinquents must be studied using the tools of neuropsychiatry, especially electroencephalographic research. The insights of earlier researchers, such as Charcot (e.g., his definition of hystero-epilepsy, the hypothesis that symptoms express and gratify wishes), as well as moderns and contemporaries (Alexander, Selesnick, Walsche, Sole, Di Tullio, Noyes) are reviewed. The location of emotional states in temporal lobe and the influence of the hypothalamic region on behavior, as well as genetic influences, such as chromosomal aberrations and linkages between the XYY karyotype and aggression are cited. Twelve bibliographic references are appended.