To provide greater support for students as they transition to ninth grade, the Texas Legislature funded the Texas Ninth Grade Transition and Intervention (TNGTI) grant program. TNGTI grantees implemented a variety of supports to at-risk students transitioning to ninth grade, including a summer transition program, an early warning data system, and research-based interventions targeted to meet student needs. The study examined the effectiveness of the supports schools provide under the TNGTI grant program. Specifically, the study compared the performance of students who participated in the TNGTI summer transition program to similar students who did not participate using a propensity score stratification approach. Students' ninth grade attendance and performance on math and reading Texas Assessment of Knowledge and Skill (TAKS) assessments were the outcomes of interest. In addition, the authors examined the theory that the TNGTI program would improve student academic performance by increasing their ninth grade attendance by examining whether ninth grade attendance was a mediator for academic achievement.