A Precious Fountain is a work of liturgical ethnography that probes the rich liturgical life of one worshiping community whose roots and practices are at once Black and Catholic, using music as a primary lens through which to explore the community's liturgy and embodied theology. Our Lady of Lourdes community in San Francisco is part of a larger event in the American church: the emergence of a new paradigm of Catholic worship, one that is "authentically Black and truly Catholic." Mary E. McGann, RSCJ, describes how the music worship of Our Lady of Lourdes in San Francisco not only enriches that community but also is an example of how a theology of music is practiced in that parish. She offers this new genre of liturgical literature that brings to light how God's Spirit is working in the churches through the idioms, perceptions, and insights of specific ethno-cultural communities in this time of massive cultural change and globalization. Mary E. McGann, RSCJ, PhD, is assistant professor of liturgy and music at the Franciscan School of Theology at Berkeley. She is the author of Exploring Music as Worship and Theology and co-author with Edward Foley, Capuchin, of Music in the Eucharistic Prayer published by Liturgical Press.