Background: This paper describes a novel combination of inclusive methods to evaluate health and health promotion needs of service users (clients) with intellectual disability. Sixty centres provide disability services to over 900 clients with intellectual disability in the East Coast Area Health Board region of Ireland (population approximately 325 000). This is the first known triangulated large-scale approach to inclusive needs assessment of clients using regional disability services in Ireland. Method: The research included interviewer-directed surveys of 247 clients with intellectual disability (or advocates) and 180 clients with physical/sensory disability; focus groups for clients, service providers and carers; and a postal survey for centre managers. Modification of existing surveys was required for people with intellectual disability. Results: Fifty-six of 60 (93.3%) centres participated. The response rate at the client level was 98.8% (3250 refusals). Health behaviours, likes and dislikes were well described by clients and advocates. Clients identified the need for more creative therapy, physical activity, relaxation therapy and social activities. Service providers and carers emphasized more the need for speech and language therapy, counselling, occupational therapy and physiotherapy. Conclusions: Inclusive research methods can produce useful outcome measures of the health promotion needs of those with disability. Triangulation is valuable, where clients, carers and service providers are all involved in the research process.