The article follows the trajectory of Doctor Arthur Moncorvo Filho and the Instituto de Proteção e Assistência à Infância, an organization that he founded in Rio de Janeiro in 1899. It examines them within the context of the construction of Brazil's institutional network in the field of children's health assistance in the first half of the twentieth century, a process that combined philanthropic activities, scientific practices, and public investments. This philanthropic physician played a model role, as he conjoined assistance activities with the application of innovative medical techniques and proposed or called for public policies that targeted motherhood and children.