Exploiting Externalities to Estimate the Long-Term Effects of Early Childhood Deworming

I investigate whether a school-based deworming intervention in Kenya had long-term effects on young children in the region. I exploit positive externalities from the program to estimate impacts on younger children who were not directly treated. Ten years after the intervention, I find large cognitive effects—comparable to between 0.5 and 0.8 years of schooling—for children who were less than one year old when their communities received mass deworming treatment. Because treatment was administered through schools, I also estimate effects among children whose older siblings received the treatment directly; in this subpopulation, effects are nearly twice as large. (JEL: I10, O12, O15)