While college readiness continues to dominate the educational landscape in the United States, students still leave high school not ready for college. As a consequence, admissions officers need to consider all available indicators (e.g., high school performance, admissions test scores, college preparatory courses) in order to effectively evaluate prospective student applications. Predictive validity studies are one of the inherent mechanisms in the admission process and can be used to predict college performance and success. These studies ultimately are guided by the availability of data, which can be challenging to identify and procure. Although predictive validity research has played an important role in informing admissions policy in recent years, few published works appear to include a full, informative account of its role in helping to establish college readiness and the importance of identifying different sources of data for doing so. This paper aims to fill that gap, bringing together a detailed explanation of the role of predictive validity studies to investigate college readiness and success and the identification of "fit-for-purpose" data to carry out such studies and inform postsecondary admissions policy and decisions.