The purpose of this study was to determine the relative importance of specific student and institutional factors and characteristics on the retention of students at public, 4-year colleges and universities in the United States based on aggregate student cohort and institutional data. The overriding goal of this research was to identify any institutional characteristics that may improve student retention rates, which would provide administrators with valuable information for planning purposes. Hierarchical multiple regression was utilized to measure the relative effect of each of five blocks of independent variables on institutional student retention rates. Results of the study indicated that while entering student characteristics were most successful in explaining variances in retention rates among institutions, the various institutional characteristic blocks also had significant effects on student retention rates, to varying degrees. Results from this study may be instructive for college and university administrators in the institutional decision-making process.