This project evaluates the effect of a combined economic and psycho-social intervention to reduce risky sexual activity and its consequences. The main hypothesis to be tested is that risky sexual activity and resulting sexually transmitted infections (STIs) can be reduced through an intervention of counseling, regular STI testing, and positive reinforcement using cash rewards. The intervention is being implemented in a population of young people in rural Tanzania where more conventional behavioral change interventions have had limited effect in battling a generalized HIV epidemic.