The provisions contained in can. 838 of CCL refer to important issues, related to the adaptation and accommodation of liturgical law. They have always been the subject of attentive and continuous interest of the Church, in order to not only preserve the essential unity of the Roman rite (SC 38), but also to facilitate the common meeting of people with God, which, of course, should take place through prayer, but also through adapted symbols and signs and proper language of communication (SC 39-40). Issues so important for the life of the Church deserve an in-depth canonical reflection, which is why they were taken up in four chapters of the study on the adaptation and accommodation of liturgical law in light of can. 838 of CCL. In the first chapter, the presentation included introductory issues relating to liturgical law. The second chapter has become a space for approximation of the concept of adaptation and accommodation in canon law. The third chapter presents the legal regulations in the field of adaptation and accommodation. The fourth chapter focused on adaptation and accommodation inherent in legal and canonical practice. Published on September 3, 2017 by Pope Francis, the Apostolic Letter Motu Proprio Magnum principium not only altered the content of §2 and §3 of can. 838 of CCL, but it also became an important contribution to the discussion on inculturation and the related adaptations and accommodation of liturgical law in many circles.