Many students who are "eligible" for college are not "ready" for college. Readiness is much more complex and multidimensional than eligibility. Most high schools are organized to make students eligible for college admission, not make them ready to succeed in entry-level college courses. Over the past 15 years, the author has conducted research on entry-level courses that has led him to create a conceptual framework for thinking about college and career readiness in a more comprehensive fashion. He and his colleagues at the Educational Policy Improvement Center used this conceptual model to create a practical way to diagnose a school's current capacity to get kids ready for postsecondary education and prescribe programs and initiatives that are consistent with the school's culture, capabilities, and needs. This article discusses the four dimensions of college readiness: (1) development of key cognitive strategies; (2) mastery of key content knowledge; (3) proficiency with a set of academic behaviors; and (4) sufficient "college knowledge" about what postsecondary education requires. Recommendations for increasing college readiness are also offered.