Part I. General overviews of scholarship. Gregorian studies in the twenty-first century / Richard Crocker. Writings on Western plainchant in the 1980s and 1990s / David Hiley -- Part II. Early history. Jerusalem and Rome (and Constantinople) : the musical heritage of two great cities in the formation of the medieval chant traditions / Peter Jeffery. The singing of psalms in the early-medieval office / Joseph Dyer. The eighth-century Frankish-Roman communion cycle / James McKinnon -- Part III. Editions and repertories. The critical edition of the Roman gradual by the monks of Solesmes / Jacque Froger. Research on the antiphoner : problems and perspectives / Hartmut Möller -- Part IV. Analytical studies. Some remarks on Jean Claire's octoechos / László Dobszay. The offertory chant of the Roman liturgy and its musical form / Joseph Dyer. The Gregorian office antiphons and the comparative method / Edward Nowacki -- Part V. Roman and Frankish chant. The central problem of Gregorian chant / Willi Apel. Die Entstehung des gregorianischen Chorals / Bruno Stäblein. The question of the 'old-Roman' chant : a reappraisal / Paul F. Cutter. Papal schola versus Charlemagne / S.J.P. van Dijk. Introits and archetypes : some archaisms of the old Roman chant / Thomas H. Connolly. Toward a new historical view of Gregorian chant / Helmut Hucke. Gregorian chant and the Romans / Kenneth Levy. Remarks on Roman and non-Roman offertories / Andreas Pfisterer -- Part VI. Other chant traditions. The development and chronology of the Ambrosian sanctorale ; the evidence of the antiphon texts / Terence Bailey. The Beneventan chant / Thomas Forrest Kelly. The old Hispanic rite as evidence for the earliest forms of the Western Christian liturgies / Don M. Randel.