The difficulty of coordinating service provision in interagency programs is a challenge for many working in public policy. We reflect on lessons learned through evaluating two inter-agency supported housing programs for people with mental illness and propose a framework outlining components needed for well co-ordinated service provision. We specify collaborative mechanisms at the policy, agency, service and client level. The key component is the role of an ‘integration coordinator': a person who is able to facilitate relationships and ensure effective information flows. Relationships need to be actively maintained to meet the inevitable challenges that will arise in complex interagency systems. The framework is relevant to policymakers across the public sector, including mental health, drug and alcohol, aged care, and policing.