Jeff Bach integrates this study of the Pennsylvania settlement known as the Ephrata Cloister into, and contributes to, two overlapping subjects: German Pietism and colonial Pennsylvania. The book emphasises social history, gender and the fluid interactions among people from a variety of Pietist and Anabaptist groups. It is based on extensive work in German-language archival and printed sources, and offers an in-depth transatlantic perspective. The introduction outlines the important themes of the book: the mystic language developed by Conrad Beissel, founder and leader of the Cloister; Beissel's background and experimentation with radical Pietism in Germany; Beissel's arrival in a frontier known as Conestoga (Lancaster County from 1729); and the development of the Cloister. Chapter i examines Beissel's thought, tracing the influence of the mystics Jacob Boehme and Johann Georg Gichtel, Dunkers, Anabaptists and the hermit Johannes Kelpius. Beissel's most striking views, fundamental to his theology, related to gender and sexuality: God and Jesus are androgynous, as was Adam before the fall; sexual relations and marriage represent an abandonment of a marriage to Sophia (for men) or Christ (for women); men should overcome their aggressive tendencies through a two-fold rebirth. Chapter ii discusses the ideas of two other Ephrata writers. Chapter iii examines rituals such as baptism, foot washing, communion, the holy kiss and tonsure. Bach gleans descriptions from various sources, recognising that there is more evidence regarding beliefs than actual practice. Chapter iv reconstructs the lives of female celibates relative to Beissel's thought. Bach's conceptual work here is excellent; but more elaboration on specifics would have been useful. Chapters v–vii uses the rich material-culture artefacts of the Cloister, while chapter v examines its construction and layout. The sheer size of the buildings and the improbability of their construction by newly-arrived non-professionals are striking (and make the site well worth a visit). Chapter vi discusses Fraktur, or German-style artistic calligraphy, relating it to the broader religious agenda of Beissel and others, and chapter vii examines beliefs in magic, sorcery, astrology and alchemy. The annotated bibliography is useful. A few quibbles: the writing in the introduction and chapter i is at times not clearly organised. While Beissel deserves significant attention, at times the book focuses too much attention on him. And Bach's introductory assessment of early eighteenth-century south-west German society is overly bleak, although that society did suffer various crises. These are minor flaws, though. Bach accomplishes several interpretive goals. He draws out the eclecticism of Beissel's thought and that of others, competition among Pietist groups, and the fact that ‘neither Pietism nor Anabaptism existed as pure types’ (p. 28). The marginality of radical Pietists in Europe, in contrast to their major impact in the colonies, emerges clearly. Bach thoroughly addresses the errors of early historians, especially Julius Sachse, which arose from an imprecise reading of the sources. His criticism of Sachse is harsh, but generally on the mark. The book also helps set the stage for much-needed comparative studies of Pietist groups. In conclusion, this book, which has already become the authoritative discussion of the Ephrata Cloister and has received three prizes, is an important contribution to Pietist and colonial Pennsylvania history.