The AIDS epidemic has significantly curtailed the lifespan in a number of developing countries, particularly on the African continent. The purpose of this pilot project is to study behavioral responses to the AIDS epidemic using recently collected data from the Malawi Diffusion and Ideational Change Project (MDICP). Specifically, the goal is to examine how people's perceptions about local rates of infection, about their own or their spouse's HIV status and their perceived risk of infection affects their behavior with regard to decisions to get tested for HIV, to engage in extramarital affairs and to use barrier methods of contraception. Husbands' and wives' decisions will be modeled in a framework that incorporates decision-making of multiple interacting agents in a dynamic, uncertain environment with imperfect monitoring of actions. This modeling is innovative because it builds on recently developed empirical methods in industrial organization that have never before been used in this type of context. The goal of this pilot project is to develop the model, calibrate the model and evaluate its fit to the data, and explore its use in assessing the effects of interventions, such as providing incentives for HIV testing. This project will lay the foundations for a subsequent NIH and/or NSF grant proposal on the investigation of behavioral responses to the AIDS epidemic. This topic is related to aging insofar as we are studying a population that is at higher risk for premature death and therefore close, or at higher risk of being close, to the end of their lifespan. The individuals in the MDICP sample also face issues often associated with older populations, such as how to cope with the risk of disease, the burden of disease, incapacitation, and impending end of lifespan. There are also some features of the data that are more unique to this population, such as decisions about whether to engage in preventative behaviors to prevent others from contracting disease.