The person-centered individualized education program (IEP) transition planning has emerged as a primary indicator of quality services, and as a predictor for successful post-school outcomes for transition-age youth with autism spectrum disorders (ASD). However, these person-centered transition practices are not uniformly implemented across the United States. Using a combined Self-Determination Theory and Ecological Systems Theory, we examined the facilitators and barriers of implementing the person-centered transition practices for youth with ASD. We conducted interviews with 21 stakeholders including youth with ASD, parents, and professionals. The current findings indicated that person-centered transition planning practices for youth with ASD showed inconsistencies and areas of need for improvement. Four key factor levels were identified based on a theoretical framework: individual level, microsystem, mesosystem, and exosystem. There were multifaceted and dynamic transactional relationships across multiple individual- and systemic-factors with respect to the person-centered IEP transition planning.