Purpose To evaluate whether an intervention, targeting deficits in social communication, interaction and restricted activities in children and adolescents with Down syndrome and autism could lead to enhanced participation in family and school activities. Methods The intervention included education for parents and school staff about autism, and workshops to identify social-communication and daily living activities that would be meaningful for the child to practice at home and at school. Thereafter, a three-month period of training for the child followed. Outcome measures comprised evaluation of goal achievement for each child, the “Family Strain Index” questionnaire and a visual scale pertaining to the parents’ general opinion about the intervention. Results On average, more than 90% of the goals were (to some extent or completely) achieved at home and at school. The mean scores of the “Family Strain Index” were almost identical at the follow-up to those before intervention. The evaluation supported that the use of strategies, intended to facilitate activities and communication, remained largely 18 months after start of the intervention. Conclusion Despite the group involved in this study being composed of older children and adolescents, most of whom had severe and profound intellectual disability, the goal achievements and parents’ views on the intervention were encouraging.