Volume I consists of three parts: Preliminary Notions," "Historical Overview of the Liturgy," and "Liturgical Sources." Articles and their contributors include "A Definition of Liturgy," by Anscar J. Chupungco, OSB; "Liturgical Families in the East," by Ephrem Carr, OSB; "Liturgical Families in the West," by Gabriel Ramis; "Bible and Liturgy," by Renato De Zan; "Liturgy and the Fathers," by Basil Studer, OSB; "Liturgy and Ecumenism," by Patrick Lyons, OSB; "History of the Liturgy Until the Fourth Century," by Anscar J. Chupungco, OSB; "History of the Eastern Liturgies," by Manel Nin, OSB; "History of the Roman Liturgy Until the Fifteenth Century," by Anscar J. Chupungco, OSB; "History of the Roman Liturgy from the Sixteenth Until the Twentieth Centuries," by Keith F. Pecklers, SJ; "History of the Liturgies in the Non-Roman West," by Jordi Pinell I Pons, OSB; "Liturgical Documents of the First Four Centuries," by Basil Studer, OSB; "Byzantine Liturgical Books," by Elena Velkova Velkovska; "Other Liturgical Books in the East," by Manel Nin, OSB; "Liturgical Books of the Roman Rite," by Cassian Folsom, OSB; "Liturgical Books of the Non-Roman West," by Gabriel Ramis; "Liturgical Textual Criticism," by Renato De Zan; "Criticism and Interpretation of Liturgical Texts," by Renato De Zan; "Translation of Liturgical Texts," by Anscar J. Chupungco, OSB; and "Liturgical Law," by Frederick R. McManus. More than forty authors from Asia, Africa, Latin America, North America, and Eastern and Western Europe have contributed to the Handbook. Many are professors and graduates of the Pontifical Liturgical Institute in Rome. Each author, while drawing material from liturgical tradition and from ancient, medieval, and modern sources, writes also from a particular research and personal interest in a subject. Although diverse in style, the authors collectively express a spirit of fidelity to the Church, to its doctrine and tradition, and to its mission. The result is a cohesive view of the meaning, purpose, and celebration of Christian worship.