The tropes, together with the sequences, represent the main creative activity of European musicians in the nineth, tenth, and eleventh centuries. Because they were not an absolutely official part of the liturgy, as was Gregorian chant, they reflect local traditions, particularly in terms of melody, more so than the new pieces that whatever new introits, graduals, offertories or communions were composed at the time, since, in these, the authors made a deliberate effort to imitate the Gregorian style, or the sequences which are, by and large, based on a relatively small repertory of international melodies. In addition, the earlier layers of tropes represent, in many cases, a survival of the pre local pre Gregorian melodic traditions. This volume provides an introduction to the study of tropes in the form of an extensive anthology of major studies and a comprehensive bibliography, providing an useful entryway into the study of one of the most important musico-liturgical genres of the central middle ages.