Inclusion Criteria:

• Meets DSM-IV criteria for nicotine dependence with a Fagerstrom Test of Nicotine Dependence (FTND) score greater than 5
• Smokes at least 15 cigarettes daily (averaged over 1 week, within the month prior to enrollment)
• Motivated to quit smoking within 30 days at time of initial evaluation
• At least one unsuccessful attempt to quit smoking in the past year
• An expired breath CO level greater than 10 ppm and baseline plasma cotinine level greater than 150 ng/ml at initial evaluation
• Body weight of at least 100 lb
• Avoidance of nicotine replacement product use one month prior to enrollment
• Speaks English

Exclusion Criteria:

• Currently taking over-the-counter or prescription sympathomimetic agents (e.g., pseudoephedrine, methylphenidate), antidepressant agents (e.g., tricyclic antidepressants, serotonin reuptake inhibitors, bupropion, other monoamine oxidase inhibitors), or meperidine (Demerol)
• Serious medical disorders such as unstable angina or liver failure
• Abnormalities in baseline bloodwork (e.g., threefold elevation of liver function tests, electrolyte abnormalities)
• Physiologically dependent on and/or abusing alcohol or other drugs of abuse (e.g., cocaine, opiates, benzodiazepines, etc.) during the 6 months prior to enrollment (based on a clinical evaluation, which includes a self-report, and is confirmed by a positive urine toxicology screen)
• Meets DSM-IV criteria for a current diagnosis of major depressive disorder, panic disorder, or post-traumatic stress disorder
• Current or past history of bipolar disorder or schizophrenia
• Past history of major depression associated with historical evidence of suicidal or homicidal behavior, or psychotic symptoms
• Currently residing with another study participant
• Presence of suicidal or homicidal ideation
• Significant impairment of social or occupational functioning, either at time of initial evaluation or during the trial
• Known hypersensitivity to selegiline hydrochloride