From three different but complementary perspectives, Nationalism on the Iberian Peninsula During the Early 20th Century analyzes relevant aspects of the nationalism movements within the Spanish State. Each perspective influences the others in a relevant dialectic relationship, as evidenced by recent developments in Spanish politics. The three authors, each from their own line of research, have come together in three parts to address Basque, Catalan, and Galician nationalism between the end of the 19th century to the middle of the 20th century. The objective is to have a more complementary vision of these three peripheral nationalisms in the contemporary Spanish State, not as isolated nationalisms, but as perspectives influenced by one another.