This chapter introduces the book’s methodology, arguments, and scholarly significance. Most works on women and early modern religion focus on nuns, holy women, or religious “deviants,” and emphasize rising hostility toward female autonomy as officials moved to enclose unmarried women and intensive female religiosity (e.g. mysticism, asceticism). This book takes a different approach and examines ordinary laywomen, particularly the broad population of non-elite women who frequently lived outside of both marriage and convent in colonial Spanish American cities. Through an analysis of approximately 550 wills, as well as a variety of other source materials such as hagiographies, religious chronicles, and ecclesiastical records, this study argues that the complex alliances forged between non-elite single women and the Catholic Church shaped local religion and the spiritual economy, late colonial reform efforts, and post-Independence politics in Guatemala’s capital.