Schools and school systems are experiencing an instructional support gap that results in limited opportunities for educators to analyze, reflect on and improve research-based practices for ELLs so that outcomes for culturally and linguistically diverse students can change. To address this need, an inter-disciplinary research team from the Center for Equity for English Learners, comprised of educational leaders, teachers, researchers, and content experts developed a classroom observational instrument—the Observation Protocol for Academic Literacies (OPAL). The OPAL is intended for teachers, educational leaders, coaches, and others to conduct focused classroom observations for three potential purposes: research/evaluation, professional development, and coaching. In this article the authors introduce the OPAL’s research base, describe how to use the OPAL tool, and provide examples of the applied use of the OPAL to support professional learning and evaluate a three-year school reform effort.