Background: Clinical experience has proven thus far that a monodisciplinary treatment approach to behavioural and psychiatric problems in persons with intellectual disability (ID), such as psychotropic medication or behaviour modification programmes, has yielded limited success. It is clear that the complexity of behavioural and psychiatric problems in this population calls for a treatment approach from different perspectives. Methods: A multidimensional treatment approach to the persons with ID who suffer from behaviour problems and psychiatric disorders is described. Results: Four dimensions--biological, psychological, social and developmental--are represented as well in an integrative diagnosis as in an integrative treatment, embodied by cooperation of different professionals, such as a psychiatrist, psychologist, pedagogues, social worker, nurse and, where possible, the person's caretakers. The developmental dimension receives a salient attention of assessors. By introducing the developmental dimension in diagnostics and treatment, the bio-psycho-social dimensions are set in a new context, more appropriate for persons with ID. Conclusion: The integrative treatment should not be primarily directed towards the symptoms of the disorder but towards restoring a persons mental well-being. The disorder is combated through treatment of the underlying processes that have led to its onset. Different treatment methods from different perspectives may be applied. Strategy and methodological procedures of an integrative treatment are discussed by way of case presentations.