Co-production is currently one of cornerstones of public policy reform across the globe. Inter alia, it is articulated as a valuable route to public service reform and to the planning and delivery of effective public services, a response to the democratic deficit and a route to active citizenship and active communities, and as a means by which to lever in additional resources to public service delivery. Despite these varied roles, co-production is actually poorly formulated and has become one of a series of 'woolly-words' in public policy. This paper presents a conceptualization of co-production that is theoretically rooted in both public management and service management theory. It argues that this is a robust starting point for the evolution of new research and knowledge about co-production and for the development of evidence-based public policymaking and implementation.