We assess the impact on teenage childbearing as well as student knowledge, attitudes, and behavior of a typical HIV/AIDS teacher training program in the Cameroon. Applying a regression discontinuity design identification strategy based on the key administrative criterion that determined program deployment, we find that 15–17 year old girls in teacher training schools are between 7 and 10 percentage points less likely to have started childbearing, an objective proxy for the incidence of unprotected sex. They are also significantly more likely to have used a condom during their last sexual intercourse. For 12–13 year old girls, the likelihood of self-reported abstinence and condom use is also significantly higher in treated schools, while the likelihood of having multiple partners is significantly lower. Copyright © 2010 John Wiley & Sons, Ltd.