Cigarette smoking is the leading cause of preventable death in the U.S. today. Each year, one out of every six deaths in the nation is attributable to this habit - a public health threat so severe that the Surgeon General set the ambitious goal of a smoke-free society by the year 2000.

As every smoker knows, quitting is no easy matter. Cigarettes and other tobacco products are both physically and psychologically addictive, principally because they contain a powerful drug - nicotine. Therefore,...