A conceptual model of dentists' treatment decision-making is discussed. The model suggests that dentists do not use a hypothetico-deductive process for the diagnosis of caries. Rather, caries is identified through a process of pattern recognition that in most instances is inextricably linked to intervention decisions. Individual dentists have inventories of caries scripts that, when matched by a particular clinical presentation, lead to decisions to treat. The scripts comprise salient factors that are dependent on individual dentist's characteristics and biases, and thus vary substantially across dentists. The scripts tend to be complex, highly visual, and difficult to describe. All of these characteristics suggest that efforts to improve dentists' caries-related treatment decisions should acknowledge this knowledge structure and be designed to change the salient factors or interpretations of salient factors within the context of the caries script.