Changes in patterns of delivery of mental health care over several decades are putting pressure on primary health and social care services to increase their involvement. Mental health policy in countries like the UK, Australia and New Zealand recognises the need for these services to make a greater contribution and calls for increased intersectoral collaboration. In Australia, most investment to date has focused on the development and integration of specialist mental health services and primary medical care, and evaluation research suggests some progress. Substantial inadequacies remain, however, in the comprehensiveness and continuity of care received by people affected by mental health problems, particularly in relation to social and psychosocial interventions. Very little research has examined the nature of the roles that non-medical primary health and social care services actually or potentially play in mental health care. Lack of information about these roles could have inhibited development of service improvement initiatives targeting these services. The present paper reports the results of an exploratory study that examined the mental health care roles of 41 diverse non-medical primary health and social care services in the state of Victoria, Australia. Data were collected in 2004 using a purposive sampling strategy. A novel method of surveying providers was employed whereby respondents within each agency worked as a group to complete a structured survey that collected quantitative and qualitative data simultaneously. This paper reports results of quantitative analyses including a tentative principal components analysis that examined the structure of roles. Non-medical primary health and social care services are currently performing a wide variety of mental health care roles and they aspire to increase their involvement in this work. However, these providers do not favour approaches involving selective targeting of clients with mental disorders.