The mission of the English Learners Success Forum (ELSF) is to collaborate with field-leading researchers, district leaders, teachers, content creators, and education funders to improve the supply and accessibility of high-quality K-12 mainstream instructional materials that address the linguistic and cultural needs of ELs while building smart demand to reach educators at scale – all with the goal of providing ELs full access to grade-level content and quality learning. Unlike most efforts that aim to improve EL learning outcomes, ELSF focuses exclusively on ensuring that full-year core instructional materials guide teachers in addressing these students’ varying needs. We do this by connecting English learner experts and quality curriculum developers through participatory review cycles that leverage specific language criteria in ELA and mathematics to improve materials. We also provide concrete examples and clear guidance to those developing content, including districts, schools, teachers, and curricula developers.