One of the goals of college student development professionals is to help undergraduate students develop a meaningful sense of personal identity. Early in the history of the profession, practitioners borrowed freely from related fields such as sociology and psychology to guide their practice, but beginning around the 1960s, scholars began in earnest to develop their own unique body of literature. In this work I examine the development of that scholarly work as it relates to identity development—specifically the evolution of understanding around the issues of sex and gender identity development. Beginning with William Perry, whose work has impacted so many theories that followed his, I review the work of Nancy Chodorow, who was among the first to note that student development theory based on male samples disadvantaged women, Marcia Baxter-Magolda, Carol Gilligan, Ruthellen Josselson, Mary Field Belenkey, Blythe McVicker Clinchy, Nancy Rule Goldberger, and Jill Mattuck Tarule…and…. I discovered that each of these scholars approached sex and gender from a binary, essentialist, deterministic position which served to limit the understanding of sex and gender issues in the field of college student development. During the same period, work in the fields of anthropology, gender studies, psychology, sociology, and women’s studies were greatly expanding their understanding of sex and gender as components of identity. In this work I identify the deficiencies and limitations in the research in the field of college student development related to sex and gender identity development; note the challenges to our work with college students because of those deficiencies and limitations, and make practical recommendations to three groups of professionals who operate in the field of college student development—theorists and scholars, practitioners, and educators and provide a model for efficiently effecting change in the field.