Transition partnerships are considered a key factor in fostering transition to adulthood for young people with intellectual disability (ID). The aim of this research was to analyse the transition partnerships between services and projects that support young people with ID in their transition to adulthood from the perspective of the professionals involved. Method: Semistructured interviews were conducted with 45 key professionals from different postschool and school projects to obtain information regarding the main problems found in coordinating the services, the causes of these problems, and suggestions for improvement. Results: A lack of continuity was highlighted in the support for young people with ID during the transition process. Insufficient information and collaboration between services and professionals and a lack of leadership were the main problems perceived by professionals. Conclusions: Our research stresses the need for clear guidelines to be established regarding the distribution of roles and responsibilities between the professionals and services involved in transition. Improving communication processes between professionals and between them and young people and their families is underlined as a way to help young people with ID in their transition to adulthood. Reinforcin g the role of the local area is also recommended