It is not known how ninth-grade regular education teachers perceive the unique stressors and challenges for students with autism spectrum disorders transitioning from middle school to high school. In addition, it is not understood how ninth-grade regular education teachers perceive their role integrated in the overall support system from parents and school administrators for students with ASD as they transition to high school. This qualitative phenomenological study examined ninth-grade regular education teachers' perspectives regarding students with ASD transitioning from middle school to high school. The study focused on three main areas of unique stressors and challenges for students with ASD, the roles of school staff, and the professional development and training needs of ninth-grade regular education teachers. Participants were ninth-grade regular education teachers at a public high school in a school district in Southeastern, Pennsylvania. Interviews were conducted via Zoom with twelve participants. The focus of the study shared the experiences of regular education teachers who support students with ASD transitioning into high school. The findings of this study suggest that school district administrators consider further faculty development specific to ninth-grade regular education teachers for supporting students with ASD in the high school setting. [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.]