In recent years, a renewed debate has developed around the potential for modified tobacco products to play a role in reducing tobacco-related harm. During the 1960s and 1970s medical experts recommended to smokers who could not quit that they switch to cigarettes with lower tar and nicotine content. At the time, survey data suggested that smokers who switched did not compensate for the reduction in nicotine by increasing their intake. However, public health scientists were hindered in their ability to evaluate the population impact of the reduced tar strategy by a limited understanding of nicotine addiction. Smoking dependence was seen as primarily psychological and social, rather than pharmacological or biological, until the late 1970s, when addiction researchers began to apply experimental techniques from other forms of drug abuse to study smoking behavior. This history has important lessons for current discussions about tobacco harm reduction and regulation of nicotine delivery.