The reform of the liturgical books conducted in Muscovite Russia in the mid-17th century was an alignment of Russina liturgical usage with contemporary Greek practice. Historians have up to now generally accepted the "official" interpretation of the reform as a "correcting" made on the basis of ancient Greek and Slavic sources. In fact, the reform was based exclusively on "contemporary" sources chiefly the 1602 Venice "Euchologion" (Greek) and 17th century South-Slavic editions from Kiev and Striatin. Far from being a "return to sources", or a "correction", the reform consisted simply in the uncritical transposition of contemporary Greek practice onto Russian soil. The first part is an historical overview of the events and of the chief personages involved in the reform. There is a discussion of the important councils from 1654 to 1667, as well as a description of significant events. Followed by a brief sketches of the chief actors, Patriarch Nikon, Tsar Alexis, Arsenios the Greek, and Epifanii Slavinetskii, with particular focus on their role in and attitude towards the reader. We see that the reform was initiated not by Nikon, but by the Tsar, and that alinging Russian practice with Greek was part of a grand design to make Moscow the "Third Rome", the new capital of the Orthodox world. For this plan to succeed, it was necessary to reconcile Russian and Greek liturgical practices, for most Russians saw differences in ritual details as heresies on one side or the other. Thus the liturgical reform was launched and Nikon, an able administrator and close friend of the Tsar, was selected as the new patriarch to see the program through. The final part of the book contains an analysis of the content of the reform, consisting of a comparative study of the pre- and post-Nikonian editions of the Sluzhebnik (Euchologion). Particular attention is focused on the text and rubrics of the Byzantine Liturgy of John Chrysostom, which underwent the most significant changes. This comparative study confirms the fact that the reform was conducted on the basis of contemporary editions, and not of ancient sources.