This study compared interactive and noninteractive smoking cessation interventions for a population of smokers who were all members of 1 division of a managed care company. In addition, it examined whether a dose-response relationship existed. Screening was completed for 19,236 members who were contacted by telephone or mail. Of the 4,653 who were identified as smokers, 85.3% were enrolled. A 2 Intervention (interactive or noninteractive) x 4 Contacts (1, 2, 3, or 6 contacts) x 4 Occasions (0, 6, 12, and 18 months) design was used. The interactive intervention was stage-matched expert-system reports plus manuals; the noninteractive intervention was stage-matched manuals. Contact occurred in 1 of 4 series (1, 2, 3 or 6 contacts) at 3-month intervals. The expert system outperformed the stage-matched manuals, but there was no clear dose-response relationship for either intervention.