This project is developing and testing the efficacy of a new math-based coaching program aimed at improving the instructional practices of elementary and middle school math teachers. The coaching model will consist of three elements: a summer training workshop, personalized web-based coaching, and access to a library of resources to support coaching and instructional change. The project team is working with 3rd through 8th grade mathematics teachers to implement and evaluate the coaching model, randomly assigning teachers to treatment and control conditions, stratifying on grade level. The project team is evaluating the effect of the coaching model in both the concurrent and post-intervention year, as past studies have found effects only after teachers have completed the full cycle of coaching. The primary outcome measures include teachers' classroom performance as captured by the Mathematical Quality of Instruction instrument, students' perceptions of their teachers' effectiveness, and student test scores.