The transition to adulthood poses one of the most complex challenges for young people with intellectual disabilities. In order to conduct a wide-reaching and in-depth study of this process, we need to know the views of these young people themselves and their families. This article presents research designed to collect the experiences and perceptions of young people with disabilities and their families regarding perceived problems and support in their transition to adulthood in Spain. A qualitative case study method was used to achieve this. Data were collected in three stages on the following topics: educational pathway (primary and secondary school), social support networks and free time, and construction of a personal plan for the future (labour market inclusion and independent living). Various different instruments were used, including interviews, focus groups and visual methods. As for the results, the young people who participated in the study experienced difficulties with both successfully completing secondary education and continuing their education. The families in our study were not very satisfied with the guidance received from professionals upon finishing secondary school. They also complained about the lack of training options available to young people with disabilities. The participants expressed certain fears regarding social inclusion and labour market integration. They are aware that they will need help, and have doubts about whether they will receive the necessary support to progress with their plans for labour market integration and independent living. As a result of the study, we propose several recommendations to improve opportunities for the social inclusion of young people with disabilities in their transition to adulthood.