Social and emotional (SE) skills are known to be linked with many important life outcomes, including academic performance, performance on standardized college entrance exams, and college enrollment, although research on enrollment is limited. In this report, the authors present data points from a study that evaluated test-criterion validity evidence for the Mosaic Readiness Index (MRI), a composite index derived from multiple SE skill items from the MosaicTM by ACT®: Social Emotional Learning Assessment (ACT, 2021). The MRI is the weighted average of an examinee's responses to a subset of items from the assessment that estimates the likelihood of student postsecondary success (see Allen et al., in press, for more information). Specifically, the authors examined whether the MRI predicted postsecondary enrollment while controlling for other variables related to enrollment.