Intervention efficacy can be increased when the treatment is maximally matched to the needs of the client. One means of achieving such matching is through use of an expert system, a computer-based decision-making system designed to utilize client information to produce unique, matched information and interventions. An expert system can combine the individual matching possible in a clinic-based intervention and the low cost associated with a public health approach. This paper begins by discussing several alternative implementations of the expert system approach within the general context of communication theory. Second, the theoretical model and related empirical evidence which form the basis of the expert system is described briefly. Third, the details of a computer-driven, expert system intervention specifically developed for smoking cessation is described. Finally, empirical results from a study comparing the expert system intervention to three alternative interventions for smoking cessation are presented. In general, the expert system approach can provide a cost effective, viable, and efficacious means of intervening in a specific problem behavior area. Implications and potential areas of development are discussed.