This brief is designed to support practitioners, instructional coaches, and school leaders in designing and implementing procedures for choosing literacy assessments, analyzing data, setting criteria, and making decisions based on student data when implementing multitiered systems of support that accommodates English learners (ELs). Classroom teachers and EL interventionists will find this brief helpful for selecting measures, making group and individual decisions, and monitoring student progress across languages. This brief uses scientific evidence from research to share a framework for assessment and data-based decision-making to improve literacy instruction for ELs. This brief also addresses issues that school and district personnel frequently encounter when designing and implementing tiered instruction in schools that implement bilingual programs or that serve ELs in English as a second language programs.