PIP: This paper describes an individual-differences model of information exposure which reflects the needs for novelty and sensation likely inherited as survival behaviors from humankind's ancient past. The model grew out of an earlier activation model developed to explain exposure to information about public affairs. After the model's biological basis is explained, it is proposed as a theory in deductive nomological form. Propositions are then deduced from its central assumptions and a series of funded health communication studies for which it has provided guidance is described. Individual differences in the need for novelty form the basis for both identifying target audiences most likely to engage in health risk behaviors such as drug and alcohol use and risky sex, and guiding the design of appropriate and effective messages. Strategies developed which have been based upon the theoretical model have successfully induced attitudinal and behavioral changes in experimental studies. They have also reached at-risk audiences in field studies through televised public service announcements in appropriate television programming.