 Innovation in History comes mainly as a result of either a new interpretation of old (that is, already used) sources, or bringing to light unknown data and sources.Probably, Alvar's most defining methodological feature has been the permanent quest for new scientific sources, something straightforward even from his very first book (the "Accounts and Letters", by Antonio Pérez, Phillip's II secretary), but especially in his last biographies (Isabella I of Castile, Cervantes) and a research project regarding the minutes of Madrid's town hall meetings in the last decades of the 16th century.Professor Alvar has participated in 18 scientific projects and he has been leading researcher in 14 of them.