The main goals of the study are to assess benefits of higher doses of the nicotine patch prior to smoking cessation for high- and low-dependent smokers, and to investigate the potential relationship between genetic factors and smoking cessation success. There will be a two-week double-blind pre-cessation exposure to nicotine patch treatment in a sample of 240 high-dependent & 240 low-dependent smokers; half of each group will wear two 21mg nicotine patches (42mg) daily, and half will wear one 21mg nicotine patch and one comparable placebo patch daily, resulting in the following four conditions (120 subjects each) during the 2-week pre-quit period: 1) Less Dependent/21mg nic., 2) Less Dependent/42mg nic., 3) More Dependent/21mg nic., and 4) More Dependent/42mg nic. After the quit date, subjects will continue with the same nicotine dosage for the 1st 4 weeks; after that the treatment will no longer be double-blind as only nicotine patches will be used: all subjects will wear one 21-mg patch daily for 2 weeks, one 14-mg patch daily for the following 2 weeks, and one 7-mg patch for the remaining 2 weeks. The four treatment groups will be distributed over 4 sites: Durham, Raleigh, Charlotte, and Winston-Salem. After the screening visit, subjects will have 7 lab visits: at 2 weeks, 1 week, and 1 day prior to the quit-smoking date, and at 1 week, 3 weeks, 6 weeks and 10 weeks after the quit-smoking date.