Bio/Description Thomas J. Espenshade, professor of sociology and faculty associate in the Office of Population Research (OPR), is retiring after twenty-five years of teaching and research at Princeton. Tom came to the profession after having first trained to become a high school mathematics teacher. That experience, coupled with the ongoing military draft of the Vietnam War, led him to enroll in Princeton’s Ph.D. program in economics in 1966. Despite the fact that social demography eventually became his disciplinary home, Tom declined a fellowship in the field at the University of Michigan because he didn’t know what “demography” was. Expecting to focus on mathematical economics at Princeton, he discovered demography somewhat accidentally through a course from Ansley Coale and immediately fell in love with the subject. His dissertation concerned estimates of parental expenditures on children in urban United States, and he received his Ph.D. in 1972. Tom is a gifted teacher, and he assumed he would spend his professional life at a small liberal arts college much like his alma mater, the College of Wooster. But fortune intervened, and he was invited by Kingsley Davis to do a postdoctoral fellowship at the University of California–Berkeley. That experience raised his sights beyond a small-college setting to an environment where he could combine research and teaching. Nevertheless, he began his career at Bowdoin College, but then spent most of the 1970s at Florida State University. Prior to coming to Princeton, he also taught at Brown University. Along the way, Tom acquired an interest in policy research, and he spent several years at the Urban Institute in Washington, D.C., and a summer at the U.S. Immigration and Naturalization Service. Eventually, he landed in Princeton’s sociology department and OPR, where he has been since 1988. Over the course of his career, Tom has re-invented himself as a scholar every decade or so. He began working on family and household demography, and his early research on the cost of raising children became the basis for uniform guidelines for child support enforcement in the United States. Later work focused on contemporary immigration to the United States. During this phase of his career, Tom developed models and numerical estimates of the flow of undocumented migrants across the Mexico-U.S. border, and created a methodology for the first comprehensive state-level estimates of the fiscal impacts of U.S. immigrants. Tom has also worked in the area of formal or mathematical demography. Research he did as a graduate student on the historical fertility patterns of Old Order Amish in Pennsylvania contributed to the development of model fertility schedules at Princeton’s OPR. While at the Urban Institute, he extended work on multiregional demography and applied these models to retrospective marital history data to estimate how much time black and white women spend in various marital statuses over their lifetimes. More recently he has been working on population momentum with graduate students at OPR, examining how momentum fluctuates across the demographic transition and incorporating migration into population momentum models. During the past decade, Tom has become a leading figure in the sociology of education, with a special concentration on diversity in higher education and more recently on early childhood cognitive development. His prize-winning book, No Longer Separate, Not Yet Equal: Race and Class in Elite College Admission and Campus Life, published by Princeton University Press in 2009, has become a much-cited work in the ongoing discussion of affirmative action and assuring access to higher education. Alongside his immense scholarly output (more than 150 articles and 13 monographs), Tom has been a fantastic mentor and teacher for many cohorts of students and postdocs. His service and devotion to Princeton are second to none. He has served as the departmental representative and chair of the sociology department, as well as the director of graduate studies of OPR. Tom assures his students and colleagues that his “retirement” will be in name only. He will keep his assiduous formal schedule but be able to spend more time on collaborating with his dedicated graduate students. This involves continuing work on the early origins of learning gaps among pre-school children and how race and social class structure these gaps.