Aims: This study examined parental perspectives on the importance and likelihood of future adult outcomes for children with Autism Spectrum Disorders (ASD), Intellectual Disabilities (ID), or Multiple Disabilities (MD) and some of the factors that may affect parental aspirations. Methods: Parents of 105 children with ASD, ID, or MD were presented with 21 possible future outcomes and were asked to indicate how important and how likely they considered these outcomes for their children with disabilities when they become adults. Results: Parents rated the overall likelihood of their child attaining various future outcomes significantly lower than the importance they placed on these same outcomes. They mostly valued future outcomes relating to their children's personal satisfaction, safety and security over and above those relating to social participation. Parental ratings of the importance or likelihood of outcomes did not differ across the diagnostic groups. Ratings of importance were independent of the child's age, gender, diagnosis, or severity of functioning, but likelihood ratings were significantly predicted by the children's symptom severity. Conclusions: The implications of this study's findings for service development, intervention and transitioning planning, and treatment outcome research are discussed in relation to existing literature and the study's strengths and limitations.