This study explored elementary schools' implementation of an integrated three-tier model of reading and behavior supports as they participated with a statewide Response to Intervention (RtI) project. The purpose of the study was to examine the process of implementing an integrated three-tier model and to explore the relation between implementation fidelity and student outcomes. Implementation fidelity was measured using the "Planning and Evaluation Tool for Effective Schoolwide Reading Programs-Revised" ("PET-R"; Kame'enui & Simmons, 2003), "Positive Behavioral Interventions and Supports Self Assessment Survey" ("PBIS-SAS"; Sugai, Horner & Todd, 2003), and the "Positive Behavioral Interventions and Supports Team Implementation Checklist" ("PBIS-TIC"; Sugai, Horner & Lewis-Palmer, 2002). Student outcomes were measured using school-level aggregate data from the "Dynamic Indicators of Basic Early Literacy Skills-6th Edition" ("DIBELS"; Good & Kaminski, 2002) and average major discipline referrals per 100 students per day, as measured by the "Schoolwide Information System" ("SWIS"; May et al., 2002). A combination of descriptive analyses and generalized estimating equations were used to evaluate implementation fidelity over time and the relation between implementation fidelity and student outcomes. Major results included: (1) Average implementation fidelity scores improved over time although individual schools started with different scores and made various amounts of growth over time; (2) Approximately half of the elementary schools included in the study attained criterion levels of implementation during their participation with the RtI project; (3) Schools made the most amount of implementation growth between years 1 and 2; (4) Overall implementation improvements and most year-to-year improvements were statistically significant; (5) The reading implementation checklist was a better predictor of student reading outcomes than the behavior implementation checklists as predictors of student behavior outcomes; (6) The combination of reading and behavior implementation checklists added to the prediction of student behavior outcomes beyond the behavior measures alone. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]