Prevention activity often occurs at different levels of community and social network. At the smallest level it could occur among a group of drug users and their peers, at the largest level, it could take the form of international drug treaties and conventions. Clearly, there are a number of ways of facilitating changes at these different levels of community and social network. This paper describes a framework that has been used by the National Drug Research Institute. It is useful in explaining that various prevention activities can operate at different community levels and in different contexts, and describes their mechanisms of action. The framework borrows from, and adapts, the 'alcohol prevention conceptual model' of Holder and the 'conditional matrix' of Strauss and Corbin. The framework is limited in that it is not a fully conceptualized, data-based or theory-driven model that specifies how its elements relate to one another. Despite these limitations it has proved to be useful in planning, understanding and describing prevention activity.