Consumer behavior has long suggested the importance of prior knowledge in understanding behavior. In spite of the vast amount of research in this area, there is a vacuum regarding to what extent an individual applies his/her knowledge in decision-making situations (a concept from economic psychology). An individual may have the knowledge but might not use it or apply it when making decisions. This is of great importance, especially within a health context where decisions may result in life or death situations. In addition, operationalizations of dimensions of prior knowledge within the consumer behavior field have been inconsistent. To eliminate these gaps in prior research and extend the consumer behavior literature this dissertation draws upon the consumer behavior and economic-psychology literatures to investigate the impact of six dimensions of prior knowledge on health information-seeking and disease prevention behaviors. The case of HPV is used here to examine the theoretical relationships. This dissertation is also of particular interest to better understanding direct-to-consumer (DTC) advertising. DTC advertising usually provides information to consumers through the listing of sources consumers can go to, other than providing disease prevention information within the message itself. Hence, examining how prior knowledge impacts information-seeking and prevention behaviors can help guide the development of more effective DTC messages. Results show that information-seeking intentions are predicted by how much consumers think they know and how much of their knowledge they apply in decision-making situations. Also, consumers who have high confidence in using their knowledge are more likely to use external (as opposed to internal) sources of information. In addition, prevention behaviors are predicted by how much consumers know about the disease, how much they think they know and their experience with the disease. This investigation helps guide the development of future DTC campaigns, in terms of motivating consumers to seek additional information, and take the recommended preventative actions; based on consumers’ prior knowledge set. In conclusion, this dissertation extends the literature on the role of prior knowledge in consumer decision-making on multiple levels and provides interesting findings for future research. / text