Student development theories offer frameworks for better understanding and enhancing the experiences of graduate and professional students. Graduate and Professional Student Development and Student Affairs Ann M. Gansemer-Topf, Leah Ewing Ross, R. M. Johnson Historically, student affairs professionals have focused on the needs and development of undergraduate students. The research and theory associated with the development of college students is termed student development the- ory. This theory draws heavily on research conducted in psychology and sociology. The traditional focus of student affairs frames knowledge about and discussions on student development theory primarily within the con- text of undergraduate education (see, for instance, Evans, Forney, and Guido-DiBrito, 1998). Learning and development, however, occur across the life span, and many of these theoretical paradigms extend beyond the undergraduate environment and can be applied to students pursuing jgraduate and professional education (see Baxter Magolda, 1992; King and Kitchener, 1994; Perry, 1970; Schlossberg, 1995). Student affairs professionals, as well as other educators, use student development theory to enhance undergraduate student involvement, persistence, and learning (see, for instance, Astin, 1993; Pascarella and Terenzini, 1991, 2005). Pontius and Harper (Chapter Four, this volume) provide an example of how the concept of engagement can be extended to provide the theoretical underpinning for services that meet the needs of graduate and professional students. This chapter reviews relevant student development theories as they apply to graduate and professional students. We also make suggestions on 19 2 NEW DIRECTIONS FOR STUDENT SERVICES, no. 115, Fall 2006 © Wiley Periodicals, Inc. Published online in Wiley InterScience (www.interscience.wiley.com) • DOI: 10.1002/ss.213