A pilot program in New York City is challenging a long-held belief about cigarette smoking—that people with mental-health problems aren't interested in quitting.

The results so far are promising. Therapists say they are surprised that some patients with mental illness have been eager to join the anti-smoking program. And for some patients, giving up smoking has helped them feel more confident about other parts of their lives. The results also hold potential for helping hard-core smokers in the general population stop smoking.

Nearly half of all the cigarettes sold in the U.S. are smoked by people with a serious mental illness, according to a study in the Journal of the American Medical Association in 2000. People with schizophrenia, bipolar disorder and other mental illnesses are twice as likely to smoke as the general population, and they tend to smoke about 50% more cigarettes per day.