 He has been Visiting Fellow at the Universities of Harvard, California in Berkeley and Ohio State University, Secretary and Dean of the School of Law at the Universidad of Cádiz, and Deputy Director of the Centro de Investigaciones Sociológicas.He has been a member of the Standing Committee for the Social Sciences, European Science Foundation, and is currently a member of the Scientific Advisory Board of the European Social Survey and of the Academia Europaea.He has also been Director of the Economics and Social Science Programme, Comisión Interministerial de Ciencia y Tecnología, chairman of the Departamento de Ciencia Política y Relaciones Internacionales (UAM), and member of the Editorial Committee of the Revista Española de Ciencia Política.