This paper explores the causal relationship between primary schooling and adult HIV status in two East African countries with some of the highest HIV infection rates in the world. Using data from the most recent Demographic Health Surveys in Malawi (2010) and Uganda (2011), the paper takes advantage of a natural experiment, the implementation of Universal Primary Education policies in the mid 1990s. An instrumented fuzzy regression discontinuity approach is used to model the relationship between increased primary schooling and adult HIV status. The results indicate that in Malawi a one year increase in schooling for a girl leads to a 6-7 percent reduction in probability of testing positive for HIV as an adult and in Uganda a one year increase in schooling leads to a 2-4 percent reduction in probability of testing positive for HIV as an adult. These results are robust to a variety of model specifications. In a series of supplementary analyses a number of potential pathways through which such effects may occur are explored. Findings indicate increased exposure to primary school affects overall schooling attainment and effects adolescent sexual behavior to some extent. However primary schooling has no effect on recent (adult) sexual behavior.