Subercaseaux Rivas was born in
Santiago, Chile, in 1906. He was the son of Guillermo Subercaseaux Pérez and Mercedes Rivas Ramírez. He studied at the German High School of Santiago (Liceo Alemán de Santiago), graduating in 1923. He later entered the Faculty of Law of the
Pontifical Catholic University of Chile, but did not complete his degree. He devoted himself to agricultural activities, working on the
Virgüin estate in
San Carlos. He also traveled to
Peru as secretary of a commission of the Central Bank of Chile. He married Olga del Río Montt. == Political career ==