This paper addresses the issues of assessment and psychological interventions of mental health in people with complex communication needs of people with intellectual disability and/or cerebral palsy. The literature indicates that research data have been lacking in this area, with a dearth of appropriate assessment tools and information on how to adapt evidence-based psychological interventions for this group. Existing psychological intervention research has been characterized by case studies and quasi-experimental designs with adults with mild intellectual disability who possess relatively good communication skills. In addition, there have been a few experimental studies with a focus on anger management with this group. In light of the lack of an empiric base, clinical practice for people with complex communication needs must draw on the evidence base for the general population, and adaptations of key elements of psychological therapies. Given the paucity of research addressing the mental health issues of people with complex communication needs, there is a need for the development of mental health assessment tools that enable clinicians to directly obtain information from the individual and for building the evidence base for counseling people with complex communication needs.