This study analyzes Marian congregational song in the Roman Catholic Church in the United States from 1854 to 2010, focusing not only on the texts and music, but also on the contexts out of which these songs came. Marian devotion before 1854 is explored as well as pertinent developments in the Roman Catholic Church-particularly Vatican II-and other cultural developments. Through the quantitative and qualitative analysis of these songs, this work develops a broader understanding of how Marian congregational song developed, persisted, and changed as a mediator of Marian devotion. The survey of 120 hymnals offers a fascinating perspective on how Marian congregational song changed before and after Vatican II. These songs were so meaningful to generations of Roman Catholics and then they seem to disappear after Vatican II. This work seeks to answer the question of why? Appealing to both lay people and academics, readers are given a clear and full understanding of Marian congregational song. Also included is a chapter that explores how Marian congregational song can be meaningful to a wide range of Christians through the Magnificat.