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 teachersâ€™ 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 studentsâ€™ rate of acceleration. This is a collaborative research project with the University of Maine and 4 partner universities.