What accounts for the differences in retention and graduation rates among large public colleges and universities that serve high numbers of low-income students? To answer this question, the Pell Institute for the Study of Opportunity in Higher Education has conducted two studies to examine the institutional characteristics, practices, and policies that might account for such differences. In the first study, the authors identified 20 four-year institutions with large proportions of Pell Grant recipients--10 with higher than average graduation rates and 10 with lower than average graduation rates. Despite design limitations, the first study yielded important findings about what colleges and universities can do to improve student persistence. The purpose of the current study was to determine whether the conditions for improving graduation rates that were observed at the smaller institutions are present or even possible to create at larger public institutions, where most low-income students in this sector are enrolled. In this report, the authors describe differences in institutional policies and practices, as well as commonalities among the higher-performing institutions. They discuss differences between the findings from the previous study and this one. Finally, they consider if practices aimed at improving overall graduation rates also work for low-income students, and offer recommendations for institutions. It is their hope that the cumulative results of their two studies will be instructive for policymakers and practitioners who seek to improve the chances for success for low-income students in higher education. (Contains 13 tables, 1 figure, and 4 footnotes.)