A variation on the nature/nurture debate that comes down forcefully on the side of nurture to challenge the assumption that sex is natural. An adamant supporter of social constructionism as a theoretical basis for understanding the world, Tiefer (Urology and Psychiatry/Albert Einstein College of Medicine) critically analyzes the history of the study of sexuality, or sexology, in these essays reprinted from various popular and professional journals. Tiefer notes a dearth of good research, concluding that what exists has been hindered by definitional problems and persistent ``biological determinism.'' The author further claims that prefeminist investigations of sexuality served men's needs by focusing on physical senses while ignoring emotions. Throughout the essays, she weaves a sharp critique of Masters and Johnson, who based their pioneering study of sexuality on a biological model, which rendered their research methodologically flawed, in Tiefer's view. Repeatedly, Tiefer tries to debunk the idea that sex is a natural act. Her argument is strong, using analogies, for instance, that compare learning to have sex to learning to ride a bike: It requires instruction, guidance, and practice. Several of the essays serve to flesh out the old debate within feminism of ``sameness versus difference,'' which attempts to determine whether men and women are essentially the same or different, since sexual theory evolves differently depending upon the presupposition. For Tiefer, the project facing sexologists is ``to define and locate sexuality in personal, relational, and cultural, rather than physical, terms.'' Given this emphasis on culture, rather than biology, however, the fact that she waits until the concluding chapter to admit her neglect of race and class in considerations of sexuality is a serious shortcoming. Despite a few too many chapters and a few too many repetitions, Tiefer handles her challenge to the study of sexuality with poise.