Sexual disorders fall into four categories: desire disorders (hypoactive sexual desire, discrepancy of sexual desire, sexual aversion), arousal disorders (female sexual arousal disorder, erectile disorder), orgasmic disorders (premature ejaculation, male orgasmic disorder, female orgasmic disorder), and sexual pain disorders (dyspareunia, vaginismus).

Sexual disorders may be caused by physical factors, individual psychological factors, and interpersonal factors. Organic causes include some illnesses, infections, and damage to the spinal cord. Certain drugs may also create problems with sexual functioning. Individual psychological causes are categorized into immediate causes, such as anxiety or cognitive interference; prior learning; emotional factors; and behavioral or lifestyle factors. Interpersonal factors include conflict in the couple's relationship and intimacy problems.

Therapies for sexual disorders include behavior therapy (pioneered by Masters and Johnson) based on learning theory, cognitive-behavioral therapy, couple therapy, specific treatments for specific problems (e.g., stop-start for premature ejaculation), and a variety of biomedical treatments, which include drug treatments (e.g., Viagra) and surgery.

A number of criticisms of sex therapy have been raised, including concerns about the research methods used to evaluate the success of Masters and Johnson's therapy, the lack of evaluation research on recently developed therapies, the medicalization of sexual disorders, and the entire enterprise of identifying and labeling sexual disorders.