Response to intervention (RTI) can be both a system for providing early interventions to struggling students and a special education diagnostic tool for evaluating and identifying students with specific learning disabilities. Contributing to the very limited literature on state-level approaches, this report describes how nine states define and support RTI at the state level. Despite the growing attention, little has been published on the state-level approach to RTI. This report expands the limited research base by providing descriptive information on state-level RTI policies and procedures in nine states: Arizona, Arkansas, California, Illinois, Nevada, New Mexico, Pennsylvania, Utah, and Washington. While the focus is on West Region states: (Arizona, California, Nevada, and Utah), RTI practices in five states outside the region (Arkansas, Illinois, New Mexico, Pennsylvania, and Washington) provide additional insights into state-level approaches to RTI. The study addresses the following research questions: (1) How is RTI defined in the nine study states, and how are RTI efforts supported at the state level? and (2) What considerations do state respondents report about developing state RTI policies and procedures, and how have their states addressed them? Four appendices are included: (1) Profiles of state approaches to response to intervention; (2) Data collection and study methods; (3) Interview protocol; and (4) Documentation review summary sheet. A list of 44 state-specific resources used in document review is also included. (Contains 4 tables, 10 notes, and 3 boxes.) [This report was prepared for the National Center for Education Evaluation and Regional Assistance, Institute of Education Sciences (IES) by Regional Educational Laboratory West administered by WestEd.]