Much research shows that teacher data use relates to increased achievement for students, but teacher capacity to use data can be limited. Recent investment in "the Science of Reading" provides opportunities to explore how teacher's data use through "Multi-Tiered Systems of Support in Reading (MTSS-R)" relates to instruction. This study surveyed teachers in 24 districts involved in a Science of Reading initiative and interviewed district leaders. We found teacher data use was significantly related to confidence teaching some elements of reading (e.g. phonemic awareness, phonics, fluency, oral reasoning, and complex text) but not all (e.g. oral language, language structure, writing, comprehension, and vocabulary). Leader interviews revealed that the initiative had strong implementation, and leaders believed it was raising student achievement.