This rejoinder provides a reply to comments on a middle school college readiness index, which was devised to generate earlier and more nuanced readiness diagnoses to K-12 students. Issues of reliability and validity (including construct underrepresentation and construct-irrelevant variance) are discussed in detail. In addition, comments from Lazowski et al. and Mattern et al. provide a useful summary of areas where more college readiness research is needed. This rejoinder elaborates on those essential next steps, including deploying readiness indicators in school settings. Advances in the measurement of noncognitive skills will require more validity research using more contemporary data from authentic school settings. Still, the middle school college readiness index is a promising proof of concept, demonstrating the utility of diverse, early measures to support targeted, timely interventions.