We examined the ability of a provider-initiated, minimal-contact intervention to modify the smoking behavior of ambulatory clinic patients. Smokers at two outpatient sites were assigned to one of three groups: provider intervention only (PI); provider intervention plus self-help manual (PI/M); and usual care (control) group (C). The physician message emphasized the patient's personal susceptibility, the physician's concern, and the patient's ability to quit (self-efficacy). The nurse consultation concentrated on benefits and barriers associated with stopping, and on strategies for cessation. Telephone interviews were conducted with the 250 participants within a few days of their clinic visit and again at one and six months. Both PI and PI/M proved to be superior to usual care in motivating attempts to quit at both one-month and six-month follow-ups, and logistic regression analyses indicated that participants receiving the self-help manual in addition to the health provider message were between two and three times more likely to quit smoking during the study period than were participants in either of the other study groups.