Response to Intervention (RtI) is a framework for collecting and using data to match students to interventions of varying intensity. This study examines the implementation of RtI in Grade 1–3 reading in 13 states during the 2011–12 school year, focusing on 146 schools that were experienced with RtI. Full implementation of the RtI framework in Grade 1–3 reading was reported by 86 percent of the experienced schools. Fifty-five percent of these schools focused reading intervention services on Grade 1 students reading below grade level, while 45 percent of the schools also provided reading intervention services for Grade 1 students reading at or above grade level. Students who scored just below school-determined benchmarks on fall screening tests, and who were assigned to interventions for struggling readers, had lower spring reading scores in Grade 1 than students just above the threshold for intervention. In Grades 2 and 3, there were no statistically significant impacts of interventions for struggling readers on the spring reading scores of students just below the threshold for intervention.