The article draws attention to a number of research initiatives in the area of liturgical plainchant, which have brought together scholars of different countries and disciplines. The number of primary sources is so great that cooperation is essential. In the first phase of modern scientific research, monks of the Benedictine Abbey of Solesmes played a crucial role, their combined efforts being rivalled by very few individual scholars. In the last quarter of a century, databases and computerized projects have been developed to which scholars from different countries can contribute and from which they can draw information, and these have to some extent replaced earlier communal efforts. When the seemingly uniform facade of plainchant is inspected closely it resolves itself into a multitude of overlapping traditions and styles: how many and how widespread they are can only be determined through international cooperation. Later stylistic phases, especially from the eleventh century onward, are influenced by a preoccupation with music as an aural reflection of the harmony of the universe.