š AbstractBackground During the last decade, there has been a growing interest in outpatient support services for persons with intellectual disability (ID) and psychiatric and/or behavioural problems and their families. In this study, we explore the family burden that is associated with children or adults with ID and behavioural or psychiatric problems living at home. Method The research group consisted of  clients of In Casa, a project of outpatient treatment. Their average age is  .  years and their average IQ  .  . The Reiss Screen for Maladaptive Behaviour (adults) or Reiss Scales for Children's Dual Diagnosis (children) and the Nijmegen Family Situation Questionnaire have been administered. Results About  % of the children and  % of the adults living at home and referred to In Casa have severe psychiatric or behavioural problems as measured by the Reiss scales. The dual diagnosis has a more negative impact on the family situation than the condition of ID only.