This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book focuses on several London parishes during the long sixteenth century, sometimes reaching into the medieval period or several decades into the seventeenth century for context. It aims to afford an exploration into the varied experiences of the parish communities throughout the era of the long Tudor era. The book demonstrates how London experienced a much greater, more fundamental cultural transformation than one might expect from examining more theologically oriented studies of the era. As implied in the sketch of Tudor London’s demographic characteristics, parishes were part of the cultural and social fabric of the city long before the Tudor era. From the twelfth century, when Londoners filled their city with small neighborhood parishes, through the Tudor period and beyond, those parishes were treated by the church and the government as a single system of basically equal components.