Special educators are the primary implementers of evidence-based practices (EBPs) for school-aged students with autism. Twenty-eight strategies and interventions have been categorized as "evidence-based" with demonstrated efficacy for children and youth with autism (Steinbrenner et al., 2020). However, the research-to-practice gap persists, with inconsistent training and implementation of these practices to meet the needs of students in authentic school settings (Hsiao & Sorensen Petersen, 2019; Knight et al., 2019). Due to the recency of the EBP movement in education, novice special educators transitioning from preparation programs into their first years in the profession are well-positioned to increase EBP implementation. Teachers' knowledge and beliefs about EBPs begin to form early in their careers and exert influence over their teaching practice. Discerning the elements of training, context, and perceptions that impact the implementation of EBPs can support the translation of these practices from controlled research settings into everyday classrooms. A cross-sectional online survey of 137 novice special educators in North and South Carolina gathered self-reports of their knowledge, perceptions of social validity (i.e., acceptability and feasibility), and frequency of use of 12 EBPs for students with autism. Follow-up interviews were conducted with a purposive subsample of ten teachers to explain and expand upon the quantitative data. Overall, teachers' knowledge, perceptions, and use of EBPs were closely linked. Positive behavior supports and visual schedules emerged as the most accepted and implemented practices. The use of EBPs was primarily driven by teachers' knowledge of the practice and judgment of its social validity. Completing a pre-service research methods course was the only training element associated with more frequent use of EBPs, underscoring the importance of preparing teachers as informed consumers of research. The thematic analysis revealed how teachers evaluated practices through a broad conceptualization of social validity, including assessing an EBP's alignment with students' needs and goals, its feasibility, its generalizability across students and settings, and its compatibility with professional values. Taken together, the results have implications for improving pre-service and in-service training of special educators, particularly by developing the professional wisdom they need to implement EBPs most effectively. [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.]