Nicotine is almost universally believed to be the major factor that motivates smoking and impedes cessation. Authorities such as the Surgeon General of the USA and the Royal College of Physicians in the UK have declared that nicotine is as addictive as heroin and cocaine. This book is a critique of the nicotine addiction hypothesis, based on a critical review of the research literature that purports to prove that nicotine is as addictive drug. The review is based on a re-examination of more than 700 articles and books on this subject, including animal and human experimental studies, effects of `nicotine replacement therapies’, and many other relevant sources. This review concludes that on present evidence, there is every reason to reject the generally accepted theory that nicotine has a major role in cigarette smoking. A critical examination of the criteria for drug addiction demonstrates that none of these criteria is met by nicotine, and that it is much more likely that nicotine in fact limits rather than facilitates smoking.