The postsecondary education system in the United States has expanded in recent decades. Between 1955 and 2005 total fall enrollment in degree-granting institutions rose from 2.6 to 17.5 million, and the college enrollment rate of high school graduates increased from around 45 to 70 percent during the same period (NCES 2008). To accommodate this growth, the number of institutions more than doubled during the same period (reaching forty-three hundred by 2006), and existing institutions expanded. From a modernization/industrialization perspective, such growth should have narrowed class gaps in college attainment by fostering high rates of educational upward mobility (Kerr et al. 1960; Parsons 1970; Treiman 1970). Underprivileged high school graduates should disproportionately benefit from this expansion, as new avenues of upward mobility open to them. Some scholars cast doubts on this optimistic view, predicting 570persistent class inequality in higher education (Jencks and Riesman 1968). Indeed, a plethora of studies continues to document class-based gaps in college attendance.