Background: Very little is known about young people with intellectual disabilities who experience additional mental health problems. The perspective of service providers has been highlighted as one unresearched area. Method: Semi-structured interviews were completed with senior service providers. Aims: (1) to explore experiences of working with young people with intellectual disabilities and additional mental health problems and their families; (2) to examine views on services' ability to meet the needs of this group. Results: Service providers identified a gulf between current policy and the reality for this group, not least in terms of all agencies working in partnership. All agencies described instances when young people in this group fall through gaps between services. Interviewees identified a range of factors that promote good outcomes. Conclusions: The results suggest that the focus of current policies to promote joint working needs to be broadened beyond health and social services to ensure much improved links with education providers and the voluntary sector if the needs of this group are to be met.