In the early 1970s, American Jews were, on the whole, centrist and conventional. Most were married, and most to other Jews. Their largest religious denomination was the Conservative movement, with its bland, spacious suburban synagogues, representing the middle ground between fusty tradition and full-forced reform. This was a community that seemed to have settled into a comfortable status quo, steadily assimilating in the postwar years and ascending into the middle class. Still, there were signs that when it came to actual religious practice, a younger generation, coming of age during the 1960s, found this stability stultifying. The desire for change could be felt bubbling from below. In 1972, the first female rabbi was ordained. Two-thirds of Jews under 30 belonged to no synagogue at all. But in cities such as Boston, New York, and Washington, D.C., groups of young, well-educated Jews had begun informally worshiping and studying together, eschewing institutional supervision and their parents’ conformity. At one such communal gathering, known as Havurat Shalom, just outside Boston, three 20-somethings decided to produce a religious book …