This article outlines the evidence upon which best practice guidelines for transition to adulthood for young people with physical and developmental disabilities were developed in Ontario, Canada, through consensus activities. Evidence was gathered from published and unpublished literature and focus groups with young people, parents, community members, service providers and policy makers across the province. The evidence was then synthesized and analyzed by an expert panel. Guidelines were developed in the areas of collaboration, capacity-building, information, education, and research. This article focuses on the findings of this project as they relate to transition services and care. These best practice guidelines for the transition to adulthood for young people with disabilities offer a starting point to encourage service providers to work collaboratively with young people, parents, communities, governments, and researchers. The evidence from this project supports a move away from purely service-driven models of transition to holistic, lifecourse/lifespan approaches. Recommendations for future study and collaborative knowledge dissemination are provided.