Diffusion theory can profitably be applied to a range of health problems and interventions. This paper uses the case of tobacco to illustrate this process. The diffusion of innovations model refers to the spread of new ideas, techniques and behaviours or products throughout populations. Those who adopt at different phases of the process tend to differ in predictable ways, such as age, sex, residence, socioeconomic status and level of access to communications, each of which can be employed to affect the overall rate of adoption. A series of perspectives are employed to examine aspects of the diffusion process for tobacco use. Examples from the tobacco areas are used to illustrate ways in which the diffusion model can be applied in the field. Applications of the model for prevention are presented and discussed.