The planning and implementation of effective transition services for students with Autism Spectrum Disorder (ASD) have emerged as crucial aspects of middle school special education. This action research study examines the impact of professional development and collaborative practices on improving transition services for middle school students with ASD in a kindergarten through high school unified school district situated in various unincorporated areas of Maricopa County, Arizona. Five middle school special education teachers working with students in grades seven and eight were participants in this study. Employing a mixed methods approach, this study sought to assess the knowledge gained and perceptions of these educators concerning transition planning and implementation. The innovation involved equipping the participants with two professional development modules developed by the Transition Coalition. These modules were designed to emphasize best practices in transition planning and transition assessment. Additionally, participants were encouraged to engage in collaborative efforts through communities of practice (COPs), fostering interaction with district departments, external agencies, and fellow special education staff. The aim of this collaborative endeavor was to enhance their ability to prepare students for the transition from middle school to high school and ultimately adulthood. The findings of this study underscore the critical need for ongoing professional development for middle school teachers to augment their knowledge base and implementation of transition services for students with ASD. Improved readiness for the high school transition and the path to adulthood is a direct outcome of such professional development. Moreover, this research underscores the significance of COPs in facilitating collaboration among special education teachers, both within peer networks and across departments, leading to improved outcomes for students with ASD. This study contributes to the body of knowledge in special education by highlighting effective strategies for enhancing transition services and advocating for the continual professional development and collaborative efforts of educators to better serve students with ASD during this pivotal phase of their education. [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.]