A vast array of data suggests that early age of smoking onset enhances the risk for development of lung cancer in adulthood. Initiation of smoking at a young age may influence the development of lung cancer because of its effect on duration of smoking. Early onset of smoking also may serve as an independent risk factor. It may increase the likelihood that smoking occurs during a critical period of development that enhances susceptibility to the adverse effects of cancer causing agents in cigarette smoke, thereby facilitating the initiation of the carcinogenic process. While evidence for the latter hypothesis derives from a variety of sources, definitive proof has proven elusive. Whether or not early age of smoking serves as an independent risk factor for lung carcinogenesis, the consensus of the public health community is that prevention of smoking onset at a young age and early cessation are keys to stemming the current lung cancer pandemic. Population approaches to tobacco prevention and control, such as measures contained in the World Health Organization Framework Convention Tobacco Control Treaty, offer the best opportunity, on the scale needed, to create a smoke-free world and bring an end to the pandemic of tobacco-related disease.