Little is known about factors impacting poor post-school outcomes for transition-age students with autism spectrum disorder. Guided by the Exploration, Preparation, Implementation, and Sustainment implementation science framework, we sought to better understand the interdependent impacts of policy, organizational, provider, and individual factors that shape the transition planning process in schools, and the subsequent process through which transition plans are implemented as youth access services and gain employment after school. We conducted focus groups with individuals with autism spectrum disorder, parents, classroom teachers, school administrators, adult service providers, and state policymakers (10 groups, N = 40). Participants described how core tenets of the individualized education planning process were not reliably implemented: planning was characterized by inappropriate goal-setting, ineffective communication, and inadequate involvement of all decision-makers needed to inform planning. After school, youth struggled to access the services stipulated in their transition plans due to inadequate planning, overburdened services, and insufficient accountability for adult service providers. Finally, a failure to include appropriate skill-building and insufficient interagency and community relationships limited efforts to gain and maintain employment. Diverse stakeholder perspectives illuminate the need for implementation efforts to target the provider, organizational, and policy levels to improve transition outcomes for individuals with autism spectrum disorder.