The 1940s marked the start of the modern style of law practice in Brazil. In this scenario, in 1948 four notable lawyers - Braz Sergio Olivier de Camargo, Luiz Lebre Pereira das Neves, Antonio Vicente da Silva Salgado and Joaquim Corrêa Lino - after successful professional experience with the law firm of Richard P. Momsen, founded the law office that today is Siqueira Castro - Advogados, which occupies a position of tradition and leadership among Brazilian business law firms.

In the 1970s, Professor Carlos Roberto Siqueira Castro joined the office. His arrival served as the impetus for further growth of the firm and continuity of a project for providing top-notch legal services.