The rise in autism and shifts in federal laws have driven a move towards inclusive education, aiming to offer equal opportunities and support for autistic students facing challenges in communication, social skills, and repetitive behaviors. Yet, placing students in the least restrictive environment can strain general education teachers without autism spectrum disorder training, impacting the quality of education. While many qualitative studies explore teacher efficacy, the focus on professional development's role remains limited. This study quantitatively assessed how the total professional development hours and autism-specific training hours predict the quality of education for autistic students in inclusion classrooms. This research was underpinned by Guskey's teacher change theory, which explores the complex dynamics of teacher professional development and its impact on student achievement. Survey responses from 140 first to fifth-grade general education teachers across Virginia, who currently or previously had autistic students in their inclusion classrooms, were analyzed using Spearman Correlation and multiple linear regression techniques. The analysis revealed that autism-specific training significantly predicted the quality of education for autistic students more than the number of general professional development hours (R2=0.452; F (2,127) =52.405, p<0.001). Future research should focus on enlarging sample sizes for better generalization, broadening the study's scope to diverse geographic regions to discern regional discrepancies in autism training requirements, and delving into additional variables linked to autism-specific training to gain a comprehensive understanding of the factors vital for successful inclusion classrooms. Additionally, longitudinal studies and assessments of specific autism training interventions can refine practices and disseminate optimal methods to sustain the long-term success and well-being of autistic students in inclusive classrooms. [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.]