OBJECTIVE:The management of interagency collaborations needs to be approached in particular, but not well defined, ways. In this paper the management and ways of working of a successful co-ordinating unit are discussed and located in the context of inter-agency partnerships. METHODS:The text is based on qualitative archival research and a critical review of practice. CONCLUSIONS:The evidence indicates that the agencies participating in the centre valued its work in facilitating inter-agency collaboration. The structural arrangements of the centre, and its modus operandi, manifest the characteristics of an 'obligational co-ordinating unit' in which success is based on establishing and maintaining appropriate interactions between partner agencies. The ways the centre operationalised the key principles of independence, member support, power and trust relations are discussed. Finally, the importance of 'environmental fit' and the impact of a changing policy environment on the centre are discussed. IMPLICATIONS:In health promotion, and public health more broadly, efforts to co-ordinate the work of agencies and their members are common. However, the precise structures and work practices that are effective rarely have a foundation in evidence or theory. This paper will contribute to our knowledge of how the work of co-ordination can be effectively undertaken in the context of agencies voluntarily entering negotiated relationships to pursue joint goals in public health.