Objective To evaluate the level of understanding and the practice of community development among Health and Social Service professionals in Northern Ireland and to assess the potential need for formal training in community development. Design A survey using questionnaires among a representative sample of health and social service professionals in Northern Ireland. Qualitative data was obtained from separate focus groups. Setting Questionnaires were self-completed by subjects contacted at their place of work. Focus groups were carried out by experienced interviewers in workplace settings. Method Ten Health and Social Services Community Trusts were selected to be representative of Trusts in Northern Ireland. Questionnaires were distributed to all 502 Health and Social Service professionals working in these Trusts. A focus group session was carried out in each of four Health and Social Services Community Trusts across the Province. Results The overall response rate was 57 per cent. Two hundred and eighty-seven questionnaires were returned from a total of 502. High response rates were obtained among health visitors, community psychiatric nurses, and social workers for disability, but groups such as community midwives may have been less well represented in our study sample (response rate 21 per cent). Over 28 per cent of subjects, particularly social workers, said they were unfamiliar with the concept of community development. Thirty- nine per cent described their knowledge as adequate and 4 per cent as good. Almost 40 per cent of the subjects said that they never used a document which had been widely distributed in Northern Ireland on a strategy for community development. Seventy-two per cent of subjects had not used the Voluntary Activity Unit's Handbook for Practitioners which had also been widely distributed in the Province. Questions on training required by professionals suggested that the majority of professionals required training in methods and techniques, values and principles, definition and clarification of professional roles, and knowledge of practice elsewhere. Focus groups reported that a high level of commitment and out- of-hours involvement was required to further enhance community development. Conclusions The majority of professional groups were positive about community development, but were unable to find or provide examples. Training needs were identified among all professional groups in this study.