The present paper aims at presenting a short history of health policies implemented in São Paulo in the 1920's and 1930's, trying to reach a more accurate understanding of the processes that led to the formulation of governmental health policies. The paper emphasizes Geraldo Horácio de Paula Sousa's contribution to the history of health administration in Sáo Paulo in the first half of the twentieth century and his proposition of a new model of health assistance based on health units that would work as the structural axis of all public health activities in the state. Finally, it focuses on the support given by Rockefeller Foundation to Paula Sousa's activities and on the disputes involved in the establishment of public health policies.