["Review of Development Economics, EarlyView. ", "\nABSTRACT\nThis paper adds to the growing evidence on the impacts of early childhood development (ECD) programming by examining one of the world's largest home visitation programmes, the Happy Child Programme in Brazil, and its impacts on child vaccination and preventable death rates. Using a difference‐in‐differences approach, we find that in the first years of implementation, the Happy Child Programme increased vaccination rates by 4.9 p.p. for children under the age of one in urban municipalities and reduced avoidable deaths by 9.3 p.p. among children under the age of one in rural‐adjacent municipalities. These findings are particularly salient considering recent negative trends in vaccination rates and the persistence of preventable child deaths in Brazil.\n"]