Subjective expectations are likely to be an important determinant of health-related behaviors in a high-HIV-prevalence environment. We use probabilistic expectations data elicited from survey respondents in rural Malawi to investigate how risky sexual behavior may be influenced by individuals’ survival expectations, which in turn depend on the perceived impact of HIV/AIDS on survival; expectations about their own and their partner’s HIV status; and expectations about HIV transmission rates. We find that subjective expectations play an important role in determining the decision to have multiple sexual partners. Using our estimated parameters, we simulate the impact of various policies that would influence expectations. An information campaign on mortality risk would decrease risky sexual behavior, while an information campaign on HIV transmission risks, which tend to be overestimated by respondents, would actually increase risky behavior. Also, the expansion of anti-retroviral therapy (ART) treatments to all individuals sick with AIDS would increase risky sexual behavior among HIV-negative individuals or those who have not been tested because individuals are aware that ART increases life expectancy, and thus reduces the cost of becoming HIV-positive.