Knowledge transfer and knowledge exchange have recently become commonly used terms in the social sciences. They imply a number of different relationships between researchers and practitioners, and between research and practice, although these have often remained implicit or underdeveloped. Drawing from the experience of designing, delivering and refining a three year knowledge transfer fellowship on community policing this article aims to critically appraise these concepts and the assumptions about ‘knowledge’ and academic-practitioner roles and relationships that underpin them. It examines the role of research in knowledge transfer and exchange collaborations and the importance of personal relationships and organisational structures in shaping and sustaining them. In so doing, we contend that the nature and scope of academic-practitioner collaborations (and the potential benefits and pitfalls inherent within them), is more meaningfully captured by a model that is introduced and sketched out in this article: ‘brokering communities of practice’.