Former Director General of UNESCO (1987-1999),  Professor Mayor is one of the founders of the Centre of Molecular Biology Severo Ochoa at the University of Madrid and of the Superior Council for Scientific Studies. He served as Spanish Under Secretary of Education and Science (1974-75), and as Minister in 1981-82. He was Deputy in the Spanish Parliament and Advisor of the Prime Minister (1977-78) and in 1987 European Parliamentary. In 1999 he left the UNESCO direction and created the Fundación para una Cultura de Paz (Madrid 2000).