Backround: The collaboration of families, therapists and educationalists has been found to be an important factor in the successful rehabilitation of children with intellectual disabilities. Previous studies have focused on the effects of therapies and the perspectives of parents on collaboration in rehabilitiation. This study aims to describe the facilitators of, and barriers to, collaboration with adults in enhancing the participation of children with intellectual disabilities in education environments. Methods: In a qualitative study, the data were collected in 2021–2022 through individual interviews with parents (n = 16), focus group interviews (n = 17) with education professionals and an online survey tool with open-ended questions from therapists (n = 309). The data were analyzed using thematic analysis. Results: Two overaching themes were identified: the prerequisites of collaboration and the sharing of expertise in collaboration from the perspective of all the participants, which included the factors facilitating and hindering collaboration. Conclusions: In optimizing the benefits of collaboration, all these themes are essential to enhancing functioning and participation. There is a need for the development of participatory practises to improve and intensify collaboration. The development of collaboration and practises should be supported by the managers. Digital solutions should be further explored in order to improve the partnership of adults and children.