Why do individuals smoke? In discussing this central question, the authors first examine a number of studies of the complex interaction between the toxicology of smoking and genetically based susceptibility to smoking-related disease, which suggest that the link between smoking and disease is more equivocal than recent epidemiological studies have claimed. Several theories of smoking recruitment and maintenance are considered and judged in the light of the known pharmacological effects of nicotine, a psychoactive drug that is the primary reinforcer in smoking. A review of psychological and behavioural evidence from animal and human studies indicates that nicotine can promote psychological comfort and performance enhancement in a variety of tasks; such effects are produced by self-titration, evidenced in smoking style, which itself is subject to some genetically imposed constraints. The effectiveness of smoking intervention and cessation strategies is assessed, and some improvements sug
