To Wait in Tier 1 or Intervene Immediately: A Randomized Experiment Examining First Grade Response to Intervention (RTI) in Reading.

This randomized controlled experiment compared the efficacy of two Response to Intervention (RTI) models - Typical RTI and Dynamic RTI - and included 34 first-grade classrooms ( = 522 students) across 10 socio-economically and culturally diverse schools. Typical RTI was designed to follow the two-stage RTI decision rules that wait to assess response to Tier 1 in many districts, whereas Dynamic RTI provided Tier 2 or Tier 3 interventions immediately according to students' initial screening results. Interventions were identical across conditions except for when intervention began. Reading assessments included letter-sound, word, and passage reading, and teacher-reported severity of reading difficulties. An intent-to-treat analysis using multi-level modeling indicated an overall effect favoring the Dynamic RTI condition ( = .36); growth curve analyses demonstrated that students in Dynamic RTI showed an immediate score advantage, and effects accumulated across the year. Analyses of standard score outcomes confirmed that students in the Dynamic condition who received Tier 2 and Tier 3 ended the study with significantly higher reading performance than students in the Typical condition. Implications for RTI implementation practice and for future research are discussed.