He has been a Principal Investigator on a large number of at-scale multi-site impact evaluations including Mexico’s CCT program, Progresa/Oportunidades, and Rwanda’s Health Care Pay-for-Performance scheme. He has published results from impact evaluations extensively in both scientific and policy journals on early childhood development, education, fertility and contraceptive use, health, HIV-AIDS, energy and climate change, housing, job training, poverty alleviation, labor markets, and water and sanitation.