As the world enters the fourth decade of the HIV epidemic, progress is finally noted in the fight against this global pandemic. Access to effective treatment has in particular increased, with beneficial effects on the health and life expectancy of people living with HIV. At the same time, in Australia and other resource rich countries, new HIV infections continue to occur at high rates and have been rising throughout the last decade. Treatment can play a role in reducing the transmission of HIV, but treatment alone is not enough and cost effective behavioural prevention approaches are available that in recent years have recieved much less priority. HIV prevention may in the future benefit from new biomedical approaches, including those that capitalise on the use of treatment. To date, however, evidence of the success of biomedical HIV prevention in real-life conditions is limited and many of those approaches will continue to rely on the behaviours of individuals and communities. These behaviours are shaped by a myriad of social factors and HIV prevention responses that reflect appropriate understanding of the complexity of human behaviour remain critical in achieving sustained success. This presentation will highlight the exciting new contributions contemporary theorising of social behaviour is making to HIV prevention.