The reauthorization of the Individuals With Disabilities Education Act (IDEA) of 2004 spurred sweeping changes for how special education students are identified in the United States. IDEA 2004 encourages schools to use Response to Intervention (RTI) as a new method for identifying special education students. As schools implement RTI, the principal becomes a key figure in determining the success of RTI. This study examines the policy ecology that influences principals' views, beliefs, and considerations of RTI in determining the school plan for implementation. We find that implementation at the school level is distinguished by two types of implementation communities, what we term "integrated" or "differentiated". Understanding the range of pressures and supports may inform district and school practitioners seeking to implement policy and policy makers as they consider the design of future policies.