Background: The transition from school to adulthood for young adults with an intellectual disability involves movement from a generally secure and supported school environment to an emerging adult life that may be characterised by a wide variation in adoption of adult roles related to employment, independent living, friendships, and day activities. Method: In this study, we investigated the perspectives of 18 mothers of young adults with either Down syndrome or Rett syndrome through qualitative semistructured interviews. The International Classification of Functioning, Disability and Health (ICF) framework was used as a conceptual basis. Results: Themes that emerged included adult roles assumed during the day, accommodation, quality of life, living a "good" life, and family impact. Conclusions: In contrast with Rett syndrome, mothers of young adults with Down syndrome described more difficult pathways to attaining stability in adult roles. Environmental facilitators and barriers emerged in the area of support, relationships, services, systems, and policies.