Fiore is a nationally recognized expert on tobacco who has written extensively on cigarette smoking and the myriad illnesses and deaths produced by tobacco. His contributions have helped to clarify the science underlying these diseases for the public as well as the medical profession. He served as Chair of all three editions the United States Public Health Service Clinical Practice Guidelines: Treating Tobacco Use and Dependence (1996, 2000, 2008). The most recent version was endorsed by 58 leading public health and medical organizations. His leadership has resulted in the development of policies that supported the Justice Department’s lawsuit against the tobacco industry in 2005, including a $150 billion plan to assist 33 million smokers to quit.