 To test these hypotheses, cigarette smokers will be recruited through flyers posted at the VA Greater Los Angeles Healthcare System in areas where smokers are likely to be present. Participants will undergo the following sequence of procedures: 1 telephonein-person screening, 2 a bolus-plus-continuous-infusion 2-FA positron emission tomography PET scanning session, 3 a structural magnetic resonance imaging scan within one week of the initial PET session, and 4 referral to a standard 12-week smoking cessation program. Rating scales for the determination of smoking-related symptoms will be collected before and during the PET scanning procedure. Smoking status and measures of nicotine exposure and metabolism will be collected during the study using participant reports, exhaled carbon monoxide CO levels, urine cotinine levels, and plasma nicotine, cotinine, and 3-hydroxycotinine levels. 