Under the No Child Left Behind Act of 2001, states created statewide systems of support, in collaboration with existing agencies, to deliver targeted assistance to districts and schools identified as in need of support. With limited personnel and resources, state education agencies partnered with outside agents to address the needs of a growing number of low-performing schools. Support and services for low-performing schools were designed to increase opportunities for schools to meet academic content and achievement standards for all students. Strong outside agents (skilled in systems change, knowledge of interventions and capacity for relationship-building) have been shown to produce changes in low-performing schools, but the long-term effect of those changes is unclear. One barrier to the implementation of the statewide system of support, and to any useful evaluation of its impact, is the presence of vulnerable populations, such as students with disabilities. Because low-performing schools tend to have larger student populations identified with academic risk factors like disability status, understanding how the partnership between state education agencies and outside agents improves outcomes for students with disabilities, specifically, is essential in evaluating the overall impact of the statewide system of support. The purpose of this research is to examine how a mid-sized state's implementation of the statewide system of support provision, as outlined in The No Child Left Behind Act of 2001, by incorporating an existing regional training and technical assistance system, one focused specifically on improving special education, impacted instructional delivery for students with disabilities. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]