This study examined 68 parents' views of the self-determination skills and capacities of their young adult children with autism spectrum disorders and intellectual disability (ages 19-21 years). Results indicated parents placed a high value on the importance of all seven component skills (i.e., choice-making skills, decision-making skills, goal-setting skills, problem-solving skills, self-advocacy and leadership skills, self-awareness and self-knowledge, and self-management and self-regulation skills) associated with enhanced self-determination. Yet, parents indicated their young adult children did not often perform these skills well. Effect sizes suggested high-magnitude differences between parents' ratings of the importance and their child's performance for each self-determination skill evaluated. Furthermore, regression analyses indicated parents' perceptions of the severity of their child's disability accounted for a significant portion of the variance in the overall ratings of their child's performance of these seven skills (26%) and overall self-determination capacity (27%). Parents who described their children's disabilities as being less severe rated their children as having higher performance levels on both measures of self-determination. Educational implications are presented along with recommendations for future research.