Many biomedical and behavioural HIV/AIDS programmes aimed at prevention, care and treatment have disappointing outcomes because of a lack of effective community mobilisation. But community mobilisation is notoriously difficult to bring about. We present a conceptual framework that maps out those dimensions of social context that are likely to support or undermine community mobilisation efforts, proposing that attention should be given to three dimensions of social context: the material, symbolic and relational. This paper has four parts. We begin by outlining why community mobilisation is regarded as a core dimension of effective HIV/AIDS management: it increases the "reach" and sustainability of programmes; it is a vital component of the wider "task shifting" agenda given the scarcity of health professionals in many HIV/AIDS-vulnerable contexts. Most importantly it facilitates those social psychological processes that we argue are vital preconditions for effective prevention, care and treatment. Secondly we map out three generations of approaches to behaviour change within the HIV/AIDS field: HIV-awareness, peer education and community mobilisation. We critically evaluate each approach's underlying assumptions about the drivers of behaviour change, to frame our understandings of the pathways between mobilisation and health, drawing on the concepts of social capital, dialogue and empowerment. Thirdly we refer to two well-documented case studies of community mobilisation in India and South Africa to illustrate our claim that community mobilisation is unlikely to succeed in the absence of supportive material, symbolic and relational contexts. Fourthly we provide a brief overview of how the papers in this special issue help us flesh out our conceptualisation of the "health enabling social environment". We conclude by arguing for the urgent need for a 'fourth generation' of approaches in the theory and practice of HIV/AIDS management, one which pays far greater attention to the wider contextual influences on programme success.