The religious left has a long, rich, and continuous history in the United States from the late nineteenth century through the twentieth century. Although the power of the religious right in recent times is far better known, the religious left is anything but new. From the 1870s to the 1980s and beyond, Americans of diverse backgrounds and religious faiths worked to transform their society to make it conform to their faith-based visions of righteousness, peace, equality, liberation from oppressive structures and traditions, and social unity. The religious left has been a basic component of both American radicalism and American civic religion throughout modern American history. This volume draws on emerging scholarship to rectify the neglect of this religious left tradition.