As the first full-length book of research in English, Our Lady of La Vang: History and Theology of a Vietnamese Devotion demonstrates that Our Lady is the ecclesial Mother of the Church in Vietnam and, at the same time, the ecclesial Mother of the universal Church. The title ""Mother of the Church,"" a title that only fully came into its own with Vatican II and the subsequent endorsement of the popes, especially Pope Francis, was inculturated in the uniqueness of Vietnamese Catholic belief and practice from the time of Our Lady's first apparition. What we see in the story and the cult of Our Lady is a piety and theology of Mary as ""Mother of the Church,"" which, as it developed, also solidified an identity of Vietnamese Catholics as such. One reason is that, just as Our Lady said she would, she inspired fortitude and endurance under persecution. The persecution of Christians in Vietnam lasted through nearly the entire nineteenth century in one form or another. As the official theology of Mary, Mother of the Church, developed more at Vatican II and in its legacy, it found a home in the hearts of Vietnamese Catholics where Mary had already been inculturated as ecclesial Mother.