American Grace is a major achievement, a groundbreaking examination of religion in America. Unique among nations, America is deeply religious, religiously diverse, and remarkably tolerant. But in recent decades the nation’s religious landscape has been reshaped. America has experienced three seismic shocks, say Robert Putnam and David Campbell. In the 1960s, religious observance plummeted. Then in the 1970s and 1980s, a conservative reaction produced the rise of evangelicalism and the Religious Right. Since the 1990s, however, young people, turned off by that linkage between faith and conservative politics, have abandoned organised religion. The result has been a growing polarisation – the ranks of religious conservatives and secular liberals have swelled, leaving a dwindling group of religious moderates in between. At the same time, personal interfaith ties are strengthening. Interfaith marriage has increased while religious identities have become more fluid. Putnam and Campbell show how this denser web of personal ties brings surprising interfaith tolerance, notwithstanding the so-called culture wars. American Grace promises to be the most important book in decades about American religious life.