The purpose of this dissertation research is to evaluate the sustained use of evidence-based practices (EBPs) with fidelity by high school personnel working with students with autism spectrum disorders (ASD) that participated in a randomized controlled trial (RCT) of a comprehensive educational intervention once the support from the researchers/coaches was withdrawn. Using surveys, observations, field notes and fidelity checklists the aim of the study is to increase our understanding of the factors that facilitate the sustained use of EBPs with fidelity at five intervention sites. Studies devoted to factors that sustain EBPs are scarce despite the imperative need to determine if effective practices are continually used once support from researchers, trainers, and coaches is withdrawn (Aarons et al., 2011; Hunter, Han, Slaughter, Godley & Garner, 2015). Using an implementation science framework, some factors that are explored are team cohesion, administrative support, staff turnover, and student outcomes. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]