Many individuals with intellectual disability will at some time in their lives engage in problem behaviors that may place them and others at risk, and reduce their opportunities for healthy psychosocial functioning. These behaviors may reach severe proportions in both intensity and frequency, necessitating intervention. Both psychiatrists and behaviorists are often approached regarding negative behaviors in intellectual disability, and each discipline offers key tools in behavioral assessment and resolution. We believe that the coordinated effort of these two disciplines affords the most comprehensive and efficacious method of assessing, understanding and treating a wide range of problem behaviors and associated psychiatric pathology in individuals with various forms of intellectual disability. This paper briefly reviews the background of problem behaviors in intellectual disability and treatment of such disturbances through separate psychiatric and applied behavioral modalities, followed by the proposed coordinated neurobehavioral model. A case series ensues, describing the successful application of the neurobehavioral model to the severe problem behaviors demonstrated by three individuals with intellectual disability related to autism, Cornelia de Lange syndrome and traumatic brain injury.