Ensuring that students are ready for college when they graduate from high school has important implications for students, educators, education policymakers, and other stakeholders. This study focuses on an examination of the relationship between the National Assessment of Educational Progress (NAEP) grade 12 mathematics assessment and college entry to identify benchmarks on the NAEP grade 12 Mathematics Assessment that are indicative of the skills prerequisite for college enrollment. Using data from High School Longitudinal Study of 2009 (HSLS:09) and the 2013 NAEP overlap sample, this study identifies college preparedness benchmarks on the Grade 12 NAEP mathematics assessment including college enrollment, selectivity of the college enrolled, remedial course-taking, enrolling in STEM major, and persistence in postsecondary education. Results provide validity evidence for the NAEP achievement levels in terms of college preparedness, especially the NAEP proficient and NAEP college preparedness indicator.