Thesis (D.M.A.)--Boston University / Francesco Cavalli was the most renowned composer of opera in seventeenth-century Venice. Though Cavalli's operas have enjoyed a surge in popularity and interest in recent years, his sacred works remain largely unknown. Cavalli published only a small portion of his compositional output, and his Musiche Sacre Concernenti of 1656 contains the largest source of his acred music in concertato style, representing a fusion of his sacred and secular compositional worlds. The purpose of this study is threefold. The first is to provide a modern performing edition of each motet governed by the same editorial principles that will serve scholars and performers by providing a performing edition based on the Gesamtausgabe tradition of complete works of a single composer. The second is to explore the musical, liturgical, and historical context and significance of his motets as pertains to executing an informed performance. The third is to promote the music of Francesco Cavalli in general. The motets of the collection include eleven psalms, five hymns, the Magnificat, and the four Marion antiphons, employable in various Vesper services of the liturgical year. Part I of this study will serve as the Critical Commentary to the edition. Chapter 1 examines Cavalli's life and work. Chapter 2 contains analyses of the motets. Chapter 3 discusses the liturgical contexts of the motets as well as the historical background of the collection in relation to Seicento Venice. Chapter 4 explores issues of performance practice such as ensemble size, voicing, the appropriate choice of instruments, pitch center, continuo practice, tempo, metric relationships, coronas, dynamics, and missing verses. Part II will present the performing edition of each motet in full score with a critical report. Sources and editorial methods will be discussed, and detailed critical notes will be provided. Appendices including the motets' texts, translations, and instrumental parts are provided.