Purpose: This study examines the ways in which school and district leaders create systems of support for classroom teachers who work with linguistically diverse students. We attempt to uncover the intentional supports leaders put in place for classroom teachers and how this may be part of a broader teaching and learning effort. Research Design: Through a qualitative case study of four districts serving different populations of English Learner (EL) students, we examine school and district leadership actions aimed at helping teachers provide instruction that is responsive to EL learning needs. In each of the four districts, three schools were chosen for in-depth analysis. Through interviews, classroom observations, and document analyses, we highlight the efforts of school and district leaders to bring about instructional change. Findings: The findings from this study are organized around five central themes. These themes include (1) resolving fragmentation by focusing on high-quality instruction, (2) creating a productive blend of district- and school-level leadership initiatives, (3) communicating a compelling rationale, (4) differentiating support systems at elementary and secondary levels, and (5) using data for instructional improvement. This study extends research on the role of school and district leaders in supporting classroom teachers' work with second language learners.