World Vision and our partner Sesame Workshop developed the WASH UP! program to promote improved water, sanitation, and hygiene (WASH) behaviors among primary school children. The program includes World Vision investment in water supply and sanitation infrastructure at schools, along with training on maintenance. World Vision, Sesame Workshop and Stanford University formed a partnership around these research objectives in 2016 and agreed to pursue a pilot impact evaluation. Zambia was identified as the ideal site, given the strong performance of WASH UP! there in nearly 200 schools across the country starting in 2015. Overall, the study generated valuable results that are relevant to the ongoing improvement and implementation of WASH UP! as an intervention; to the design of follow-on research that can quantify the impacts of the program with a high degree of confidence; and to the wider community of researchers and implementers interested in using school-based programming to catalyze broader, household-and community-scale change.