This article deals with the formation of the canon of sacred texts among the Old Believers, which determined their system of book authorities. The relevance of the topic is connected with the need to get a more comprehensive idea of the formation of the religious and social movement that received the name “Old Believers”. The author pays attention to an important aspect of the study of the Old Believer ideology, which was determined by the system of book authorities. The defenders of Old Belief followed the traditions of the scribes of Old Rus and maintained a special attitude to the text, bordering on its sacralisation. From the first steps of the reform, they turned to manuscripts and early printed books to find evidence of the illegality of introducing innovations into the liturgical practice of the Russian Church. The Story of How to Make the Sign of the Cross by Maksim Grek was cited by opponents of the church reform as an argument in defence of the negative view of the introduction of the three-fingered sign of the cross by Patriarch Nikon. It is shown that the Solovetsky monks largely determined the attitude to this work. They not only copied it, but also began to defend the authority of Maksim Grek when the representatives of the official Church expressed doubts about the sincerity of the author’s opinion on the twofingered sign of the cross. The next generations of the Old Believers continued to search for evidence of the veneration of this Athos monk by the Patriarchs and the Russian Church, in order to convince readers of his holiness. The analysis of the collections of the Old Believers helps get an idea of a completely scholarly approach to the search, which allowed the Old Believers already at the beginning of the eighteenth century to gain access to a fairly complete circle of sources on the life and work of Maksim Grek in Russia, even according to the ideas of researchers of the nineteenth and twentieth centuries, to copy them and make them known to other Old Believers. The works of Maksim Grek were of particular importance, and their study made it possible to include them in the canon of sacred texts. It is concluded that the authors of the essays and the compilers of the collections did a lot of work to strengthen the authority of Maksim Grek among the Old Believers, and the writings of the Athos monk were included in their system of book authorities.