Smokers report that they often smoke cigarettes during stressful times. Smoking and stress produce similar physiological responses such as increases in heart rate, blood pressure, and adrenaline levels. The combination of smoking and stress results in greater increases in these physiological responses compared to smoking or stress alone. Such increases are thought to be harmful to cardiovascular health. Additionally, smokers with exaggerated responses to stress may be more likely to relapse following a smoking cessation attempt. The purpose of this study is to assess the effects of paroxetine, a selective serotonin reuptake inhibitor (SSRI), on the cardiovascular response to stress after smoking.