An increasing number of observers are claiming that a biological model is more appropriate to an understanding of human sexuality than the conventional social-learning one. Such claims have prompted a perusal of the biological literature to ascertain whether the relevant evidence is convincing. The results of this review suggest that claims for the biological model are questionable since the evidence for that model either derives from animal studies (and is thus not generally applicable to human behavior) or is inconclusive, contradictory, or methodologically deficient. It is concluded, therefore, that behavioral scientists are at present on firm ground in using a social-learning, in preference to a biological, model to interpret most aspects of human sexual behavior.