He studied at the University of Valladolid, earning a degree in History, and subsequently earning a PhD. Enter 1967 and 1971 was associated professor Medieval History of Universidad Complutense de Madrid. He became a professor in that subject, serving in 1971 and 1973 in the University of Seville. From 1973 he was professor of Medieval History at the University of Valladolid. Enter 1981 and 1984 was dean of the Faculty of Arts of the University and later served as director of its Department of Medieval History. Under his tutelage was formed a generation of prestigious medievalists, including María Isabel del Val, Juan Carlos Martín Cea, Asunción Esteban Recio, Ángel Martínez Casado and Juan Antonio Bonachía Hernando. He was a founding member and chairman of the editorial Ambito, a member of the editorial board of Spanish newspaperEl Mundo century, and a member of the advisory board of the journal Historia16. In 1994, he was curator of the exhibition El testamento de Adán. In July 2002,he was appointed director of the Institute of History of Simancas. On November 16, 2001, he was elected a full member of the Real Academia de la Historia, to fill the vacancy left by Pedro Lain Entralgo, entering the same in June 2002. He was one of the largest and most prestigious specialists from Spain in the late medieval period in the Crown of Castile. He is father of the novelist Julio Valdeón Blanco. He died in Valladolid on 21 June 2009.
Awards
In February 2002 he received the honor of Castile and León Award for Social Sciences and Humanities "in recognition of research work on the medieval past, and permanent teachers and generous disposition". In 2004 he received the NationalHistory Award of Spain for his work Alfonso X: la forja de la España moderna.
Works
La muerte y el más allá: Edad Media n.º 6Universidad de Valladolid. Secretariado de Publicaciones e Intercambio Editorial, 2004.
La Alta Edad MediaGrupo Anaya, S.A., 2003.
La España medieval Actas, S.L., 2003.
Alfonso X: la forja de la España moderna Ediciones Temas de Hoy, S.A., 2003.
El retorno de la biografía : Edad Media nº 5 Universidad de Valladolid. Secretariado de Publicaciones e Intercambio Editorial, 2002.
Contestación social y mundo campesino: edad media Universidad de Valladolid. Secretariado de Publicaciones e Intercambio Editorial, 2002.
Historia de las Españas medievales Editorial Crítica, 2002.
Abderramán III y el Califato de Córdoba Nuevas Ediciones de Bolsillo, 2002.
España y el "Sacro Imperio": procesos de cambios, influencias y acciones recíprocas en la época de la "europeización" Universidad de Valladolid. Secretariado de Publicaciones e Intercambio Editorial, 2002.
Los trastámaras Ediciones Temas de Hoy, S.A., 2001.
Abderramán III y el Califato de Córdoba Editorial Debate, 2001.
Judíos y conversos en la Castilla medieval Universidad de Valladolid. Secretariado de Publicaciones e Intercambio Editorial, 2000.