This quasi-experimental study will examine the effect of mixing, matching, and layering interventions on the reading acceleration of struggling readers in grades K-3. Teachers across multiple states will collect pre- and post reading levels for approximately 500 students who are participating in one or more interventions within the Comprehensive Intervention Model (CIM) and a random sample of non-intervention students at each grade level. Additionally, teachers will collect formative data for all CIM students at weekly intervals, including text reading levels, type and layers of intervention, and teachers’ written reflections and decisions. All student data will be entered into the CIMME data system at the University of Maine Research and Evaluation Center. A secondary purpose of the study is to determine how teachers use systematic data as a component of their Response to Intervention approach, and if teacher decision-making has a positive influence on the students’ rate of acceleration. This is a collaborative research project with the University of Maine and 4 partner universities.