Nicotine is considered to be the main agent in the maintenance of the tobacco smoking habit and is largely responsible for the behavioral and physiological responses to the inhalation of tobacco smoke. This work presents advances made in the elucidation of the action of nicotine in the body—essential information for developing treatments to help people give up smoking. The book reviews the progress made in identifying nicotinic acetylcholine receptors in the brain, using the techniques of molecular biology to characterize receptors and investigate the functional differences between receptors composed of different types of subunits. Sex-specific differences in the response to nicotine, the effects of nicotine on locomotor activity, and its still-debated influence on cognitive performance are considered. The book also examines the habit-forming role of nicotine, the development of tolerance to nicotine, and the less clearly understood phenomenon of withdrawal. Also discusses some potential therapeutic strategies.