U.S. public education systems are required to provide free appropriate public education to students with disabilities in least restrictive environments that are appropriate to meet their individual needs. The practice of educating students with disabilities in neighborhood schools in age-appropriate general education classrooms and other school settings to meet this requirement has come to be known as "inclusive education." The long-standing interest in keeping students with disabilities in the same classrooms with their neighbors and peers has created a need for reform to establish equity in America’s schools. Schoolwide Integrated Framework for Transformation (SWIFT) is a whole-system school reform model provided through a national technical assistance center that addresses core features of inclusive education support for elementary and middle schools, particularly those that are chronically low performing and those serving students with the most extensive needs. We describe the development and preliminary technical adequacy of SWIFT Fidelity of Implementation Tool (SWIFT-FIT) as a means to document the extent to which schools are implementing inclusive education. Findings provide preliminary support for trained assessors using SWIFT-FIT as a valid and reliable instrument to produce evidence that describes the extent to which schools install, implement, and sustain these evidence-based practices. Researchers and other school personnel can use these data to evaluate the impact of implementation on progress as well as important student and other outcomes.