This paper sets forth an initial synthesis of the musical practices of the Marian sodalities established in the two former Belgian provinces. The musical history of the Belgian sodalities has been compiled on the basis of disparate and heterogeneous archival sources, which shed light on the musical practices of the Marian sodalities in two ways. First, they reveal the financial, human, and material resources brought together by the sodalities, as well as the close links maintained by the sodalities with the various local musical bodies. Secondly, the documents indicate two activities for which particular use of music was made: the yearly Marian feasts and the Lenten meetings for meditation. The information gathered from the archival sources can be cross-referenced here with some musical sources, most probably destined for the celebration of these feasts: 1) an international series of litany settings; 2) a corpus of musical works based on texts on the passion of Christ.