Self-regulated strategy development (SRSD) is an evidence-based practice for writing that is effective in improving the writing performance of elementary students with learning disabilities and the broader student population. In this manuscript, we provide guidance for elementary instructional coaches in facilitating a schoolwide adoption of SRSD for writing instruction. We outline the steps for instructional coaches to conduct practice-based professional development and then discuss ways instructional coaches can support teachers and oversee schoolwide SRSD implementation. Finally, we present ways that instructional coaches can be a valuable resource for teachers in differentiating SRSD instruction to meet students' needs and to track students' growth. By fostering a schoolwide implementation, coaches can harness the power of additive knowledge, increase teacher knowledge of evidence-based pedagogical practices, and increase the writing skills of all students, including those with learning disabilities.