Currently 15 percent of U.S. students receive special education services, a widespread intensive intervention with variable effects on students. Spurred by changes in federal policy, many states and districts have begun adopting the Response to Intervention (RTI) approach to identifying students to receive special education services. RTI seeks to provide a system for targeting interventions to children facing early academic challenges and identifying children with specific learning disabilities (SLD). This paper uses a difference-in-differences design to examine the effects of RTI adoption across Oregon on elementary students' disability identification and state-standardized achievement test scores. RTI adoption reduced special education identification by 1.4 percentage points (11%) and SLD identification by 0.5 percentage points (15%). RTI also caused moderately large reading test score gains for Black students (0.15 SD) and did not reduce other students' achievement. These findings suggest RTI is a promising approach to supporting struggling students.