This is a facsimile of the 1817 fourth edition of Hannah Adams's pioneering harbinger of the scholarly study of religion. The book surveys the diversity of religion, mostly of historical and contemporary Christian sects and movements but with significant inclusions of Jewish, Muslim, and "heathen" religious groups. Adams's particular contribution was the self-conscious effort to treat all religious groups on the same level and to avoid explicit or implicit judgments. She preferred to use self-descriptions where she had them. It is this non-normative approach that gives the book its historical value. Thomas Tweed's introduction discusses Adams's life and sets her and her book usefully in their context. He includes a helpful guide to the key entries.