A dynamic mathematical model is proposed to explain how information can influence the fraction of the population with a particular habit. The model includes several important factors mentioned by Fishbein and Ajzen, and Bentler and colleagues: (1) intention is central to behavior, (2) volitional deficiency means that only a fraction of those with the intention actually carry out the behavior, (3) normative influences can affect behavior and can be modeled in analogy to the mathematical formulation used for the diffusion of innovations, (4) information from a previous behavior can influence a behavior change so that recidivism for a behavior like quitting of smoking is dependent on the previous habit of smoking, and (5) persuasive communications from mediated sources also can influence intent and behavior. All the influences are incorporated in a time dependent manner. A procedure is proposed for testing the model for a habit like smoking using the results of a simple four question survey administered once. If validated, the theory can then be used to predict the results of advertising campaigns after the end of the campaign.