This article presents the Classroom Strategies Coaching (CSC) Model, a data-driven coaching approach that uses teacher formative assessment data to drive improvements in universal practices. The classroom strategies assessment system (CSAS), a formative assessment of evidence-based instructional and behavioral management practices was used to facilitate the coaching process. Results from 32 elementary school teachers who received brief coaching after participating as waitlist controls in a randomized controlled trial are presented. Teachers' practices remained stable across baseline periods. Following coaching, teachers displayed improvements toward their behavioral management goals (e.g., ds = 0.50-0.83). Results also showed meaningful reductions in the overall need for change in instruction (d = 0.88) and in behavior management practices (d = 0.68) at postintervention. Findings illustrate the benefits of integrating teacher formative assessment in coaching to improve teaching practices. Implications for practice and future directions are outlined.