D-Cycloserine Enhancement of Exposure-Based CBT for Smoking Cessation (DCSSmoking)

Inclusion Criteria:

1. Be a regular smoker for at least one year 3. Currently smoke an average of at least 10 cigarettes per day 4. Report a motivation to quit smoking in the next month of at least 5 on a 10 point scale 5. Score 20 or greater on the 16-item Anxiety Sensitivity Index (Schmidt & Joiner, 2002).

Exclusion Criteria:

1. Current diagnosis of a psychotic, eating, developmental or bipolar disorder (as determined by the SCID)
2. Current anxiety or mood disorder rated moderate or greater (i.e., CGI score of 4 or greater for an anxiety or depressive disorder or any current or recent-1 year--suicidal ideation)
3. Psychoactive substance abuse or dependence (excluding nicotine dependence) within the past 6 months
4. Current use of isoniazid psychotropic medication
5. A history of significant medical condition, such as cardiovascular, neurologic, gastrointestinal, pregnancy and/or breast feeding, history of seizure (other than febrile seizures in childhood) or other systemic illness and/or be deemed as currently unhealthy in the context of a complete physical examination
6. Limited mental competency and the inability to give informed, voluntary, written consent to participate,
7. Current use of any pharmacotherapy or psychotherapy for smoking cessation not provided by the researchers during the quit attempt,
8. Concurrent psychotherapy initiated within three months of baseline, or ongoing psychotherapy of any duration directed specifically toward treatment of anxiety or mood disorder other than general supportive therapy initiated at least 3 months prior to the study
9. Use of other tobacco products
10. Planning on moving (outside of the immediate area) in the next six months
11. Insufficient command of the English language (i.e., they cannot carry on a conversation with an interviewer in the English language or read associated text).