Leaving God for God is a study of five generations of Catholic Sisters in Britain from 1847 to 2017.  As members of the Company of Daughters of Charity of St Vincent de Paul, which traces its origins back to St Vincent de Paul and St Louise de Marillac in seventeenth-century France, they belong to the largest transnational institute in the Catholic Church. Written with access to the Daughters' archives in London and Paris this history draws on a wide range of additional sources to place the Sisters in a social and ecclesial context.  It assesses how far, at different periods between 1847 and 2017, the Sisters lived out their undertaking to serve the poorest and most marginalised in society. Their history and experience serve to illuminate Catholic voluntaryism in relation to the state and civil society but, going further, it enables exploration of the question about a distinctive practice of Catholic charity and charitable care. Other themes used to frame this history include transnationalism and cultural adaptation, lay and religious status, gender in the Church's mission at home and overseas, the interplay of national identities in Catholic Britain, the development of Marian devotional life and, above all, the historical practice of women's ministries  in the Catholic Church. The history of Catholicism in England and Scotland is seen in fresh perspective through the lens of this singular transnational community of women.  Their history, it is argued, challenges both the mainstream narrative about the nature of philanthropy and charity in Britain and the Catholic narrative about Catholic sisters in the twentieth century.