The document presented in the article dates from the time of Charlemagne and was part of his reform program of religious and intellectual life. Its origins must be sought in Alcuins’ letter of 796, addressed to Charlemagne (a copy of this letter was also sent to Arno, the Archbishop of Salzburg), which – after a failed mission to the Saxons – offered rulers a new form of evangelising the Avars. Recalling the disappointment of attempts to evangelise in Saxony, he warns against making too rapid and violent actions. They have to be taught first, and then baptised. At the end of the letter, referring to St. Augustine’s De catechizandis rudibus, he states what teachings in the truths of the faith they must receive before baptism. This letter sent to both the king and the bishop Arno gave the unknown author (editor) a framework and plan for the drafting of Ordo de catechizandis rudibus. The document appeared in the surroundings of the bishop Arno about the year 800. The word Ordo used in the title indicates that it is a kind of guide with guidelines for teaching adults before baptism. Although the title of the document was taken from the work of Saint Augustine of the same title, it differs substantially from its original. The Carolingian Ordo can be divided into four parts or sections. The first part (1-13) is a comprehensive introduction showing the need to instruct catechumens and the overall characteristics of the process of Christian initiation. The second part (14-44) includes the initiatory catechesis and provides topics covered in teaching converts. The content consists of biblical texts and the writings of various Fathers of the Church and practical instructions derived from the work of St. Augustine. The third part (45-74) presents the liturgical rites of baptism. In the fourth part (75-94), the document explains the baptismal rite itself and the other celebrated sacraments of Christian initiation – the Eucharist and Confirmation. The Ordo text ends with a call to neophytes to faithfully fulfil in practice what has been communicated to them.