Aragon was one of the kingdoms in the Iberian Peninsula during the Middle Ages, and its language was Aragonese, a language replaced by Castilian (Spanish later) in mid- and lower Aragon around the end of the fifteenth century. This article presents the most relevant linguistic characteristics of Spanish in the historical region of Aragon. Attention is paid to the presence of old Aragonese linguistic elements in Spanish spoken today, as well as to the linguistic attitudes, social uses, and legal situation of linguistic varieties in northern and eastern Aragon.