This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book focuses on the themes of gender, ethnicity and class. It shows how the Catholic Church developed into a multifaceted institution on a national scale that worked to secure and safeguard a civil society and a national identity that was distinctively Scottish. The book considers the state of Catholicism up to 1834 and begins with a brief sketch of Scottish Catholicism in the seventeenth and eighteenth centuries to reveal just how disorganised and divided the church actually was. It examines how the church reacted to liberalism, legislative reform, the rise of evangelicalism and the continued growth of Irish migration between the late 1820s and the late 1850s. The book examines the development of Catholic education in Scotland and prioritises the role played by women religious in this process.