Interagency collaboration has increasingly been viewed as an important strategy to encourage the co-ordination of healthcare. It is seen to have a number of positive outcomes, including: improved service delivery for people requiring multiple services; more efficient use of healthcare resources; and a means for managers to share the responsibility of community care and reduce organizational stress caused by pressures of increasing demand for services within a climate of cost containment. However, establishing collaborative interagency relationships can be a challenging, long-term and complex process. The present article describes some of the findings of a research project that evaluated collaborative strategies adopted and trialed by a group of four publicly funded healthcare agencies in the southern metropolitan area of Adelaide, South Australia. Key findings from the literature about the factors supporting and impeding collaboration are discussed in the light of some of the findings from the evaluation project. Some of the themes emerging from the Adelaide study include: the need for resources for change; experience of multidisciplinary work; professional barriers to collaboration; the importance of agreed aims, agendas and project ownership; and the importance of supportive leadership. This article concludes with a discussion of the difficulties and opportunities for collaboration between community-based primary healthcare agencies and acute care hospitals. The development of partnerships which are either based on trust, or on the open negotiation of power differences and professional territories, and the management of mistrust are found to be important foundations for achieving greater genuine collaboration between primary and tertiary level healthcare.