The impact of sex education on various behavioral outcomes has been well studied in the
literature. However, these studies fail to account for the simultaneity between knowledge demand
and sexual behavior, leading to inconsistent effect estimates using simple comparison of means from
randomized control interventions. A theoretical model of sexual behavior and sexually transmitted infection (STI) information
demand is proposed to motivate the discussion. We show that the effect of STI knowledge on
sexual behavior depends on how information affects the expected cost from sexual activity. We
provide empirical evidence using Philippine data that increasing HIV/AIDS knowledge delays
sexual initiation, limits sexual activity, and increases condom use among some subpopulation of
female young adults.
