This study presents longitudinal description of the association between college readiness--as measured by college readiness benchmarks set by the ACT--and a series of postsecondary outcomes of the Illinois High School Class of 2003. In addition to describing how college readiness is distributed among the cohort, this study establishes the college readiness of various groups based on select demographic characteristics such gender, race, and family income. Finally, the relationships between college readiness, student characteristics and postsecondary enrollment, persistence, and bachelor's degree completion measures are analyzed. (Contains 11 tables and 24 figures.)