The purpose of this study is to investigate the effect of gemfibrozil on nicotine reinforcement and cue-elicited craving. Other objectives of this study include screening for the ability of gemfibrozil to aid smoking abstinence during a brief quit attempt and examining the validity of using laboratory measures of tobacco dependence to predict smoking abstinence. It is hypothesized that gemfibrozil will result in diminished nicotine reinforcement, an attenuated response to smoking cues, and an increase in smoking abstinence compared with placebo. It is also hypothesized that the laboratory measures will prove valid in predicting abstinence.