This paper provides an overview of Basque catechisms published during the Early Modern period, specifically between the sixteenth and nineteenth centuries. We have established a corpus of 75 printed doctrines (including first editions and reprints), manuscripts and works identified through secondary sources. Our analysis combines qualitative and quantitative approaches to examine the religious, cultural and linguistic contexts in which these texts were produced, as well as their authorship, functions and linguistic choices. The study also includes two case studies: one concerns the doctrine by Materra, Doctrina christiana. Pierre de la Court, Bordeaux (1617), which represents the first milestone of the Counter-Reformation in the Northern Basque Country, and the other the work of Betolaza, Dotrina Christiana en romance y basquence. Pedro Cole de Ybarra, Bilbao (1596), one of the first known texts in the Southern Basque Country.