Since his return to the Philippines in 1970 after graduate studies abroad, Nebres has worked on three major areas: teaching and development of mathematics and science in the Philippines and in Southeast Asia; administration in the university and in the Jesuit Order; and leadership in the socio-political concerns of the Philippines during the years of martial law and in the early years of democratic restoration. In the 1990s, he also became more involved in the business world, particularly in the relationships between universities and business and technology.