Plínio de Arruda Sampaio Jr., sometimes simply referred to as Plininho, is a Brazilian economist, academic, and political figure. He is a retired professor of economics at the University of Campinas in São Paulo, one of the top-ranked universities in Brazil and Latin America. During his career, Arruda Sampaio Jr.'s work primarily focused on the economic history of Brazil, developmentalism, and political economy. He has also served on the editorial board of Brasil de Fato, a left-wing publication.