The article presents the first part of the translation into Russian of the famous treatise by de Saint Lambert, Les Principes du Clavecin (Paris, 1702). In the Introduction and eleven subsequent chapters, which make up the first half of de Saint Lambert’s work, the problems of harpsichord pedagogy are discussed, the basic rules of elementary music theory and musical notation are defined, and an overview of the characteristic features of the keyboard of the French harpsichord of the late 17th century is given. Here, de Saint Lambert also provides detailed and very valuable instructions for beginners on working with the repertoire, on time signatures and choosing the correct tempo of performance, on timing, on the conventions of rhythmic notation (les notes inégales). A significant amount of the text is devoted to explanations concerning the meaning and use of various ligatures in the musical text, the division of voices in tablature, &c. The translation is provided with detailed comments, including, among other things, an analysis of the content of the English translation of de Saint Lambert’s treatise by Rebecca Harris-Warrick (1984) and the German translation by Claudia Schweitzer (2000). Some minor discrepancies in the texts of the original Parisian edition (1702) and the counterfeit Amsterdam edition of de Saint Lambert’s work (c. 1710) are noted as well.