The relationship between personality and sexual compatibility in 60 married men in their early 30s was studied as part of a longitudinal study of maturing. Sexual compatibility was assessed by the men's ratings of their own and spouses' sexual pleasure, of the similarity of their sexual values, of their mutual faithfulness, and of the consideration by the spouse of the men's sexual needs. The measure was independently validated by the judgments of the men's wives of the men's excellence as sexual partners and lovers. Extensive psychological test, questionnaire, and judge ratings from the men's wives, closest male friends, and colleagues were secured. Sexual compatibility was significantly related to 39% of the more than 400 measures of adult personality and interpersonal relationships. Sexual compatibility was moderately related to sexual pleasure and satisfaction, but not to marital coital frequency. Increasing sexual compatibility was consistently related to increasing psychological maturity, interpersonal maturity, and the mutuality of the marital relationship, to effectiveness in fulfilling various adult roles, and to marital happiness.