Across the globe, schools serve students from increasingly diverse backgrounds, including those still learning the dominant language. But schools have struggled to maintain pace with the changing population, resulting in a lack of prepared teachers and subsequent gaps in student achievement. In this article, we share a theoretically grounded and research-based approach to build capacity in linguistically diverse schools through multi-faceted professional development (PD) efforts with teachers and leaders. Based on a 3-year project that successfully built foundations, structures, and supports for culturally and linguistically diverse (CLD) students in 32 urban schools in the United States, we provide readers with pertinent foci and facets to design and implement linguistically responsive practice and PD.