We analyzed data obtained from a representative sample of the smoking patients (n = 1,338) of 66 family physicians to determine predictors of attempts to stop smoking, desire to quit smoking, and successful smoking cessation. Compared to subjects who made no attempt to quit smoking, subjects who tried to quit smoking tended to be younger, had tried to quit smoking in the year prior to the study, waited longer before smoking their first cigarette of the day, had more desire to quit smoking, and had more social support for quitting. Education and cigarettes smoked per day were not independently related to the subject making a quit attempt. Desire to quit smoking was associated with an attempt to quit in the year prior to the study and social support for smoking cessation (support of spouse, second most important social contact, and physician). Desire to quit smoking was not independently related to age, education, or dependency on cigarettes (measured by the number of cigarettes smoked per day and the length of time a subject waited before smoking the first cigarette of the day). Compared to subjects who tried to quit and failed, subjects who succeeded were older, smoked fewer cigarettes per day, and waited longer to smoke their first cigarette of the day. Spouse support, support of the second most important social contact, and advice of a doctor to quit smoking were not independently related to whether or not a cessation attempt would be successful. These data suggest that successful smoking cessation requires two components: social support to make an attempt to quit and the ability to overcome dependency on cigarettes to make the attempt successful.