He combines his research interests with his position as a sociology professor, and he became the chairman of the Institute for Social Research, for the National School of Political and Social Sciences, also for the Interdisciplinary Research Center in Humanities, at UNAM. He served as President of UNAM from 1970-1972, and has been an invited lecturer at universities such as Cambridge. He was also President of the Asociacion Latinoamericana de Sociolog�a, and belongs to several international societies in sociology. He has published several articles, some of the most influential are Sociolog�a de la explotaci�n (1969), Historia del movimiento obrero en Am�rica Latina (1981), El Estado y los partidos pol�ticos en M�xico (1981), Am�rica Latina, hoy (1990), El Estado y la pol�tica en el sur del mundo (1994), and perhaps the most out standing Democracy in M�xico (1965), which has been translated and edited several times.