Studies of young American Catholics over the last three decades suggest a growing crisis in the Catholic Church: compared to their elders, young Catholics are looking to the Church less as they form their identities, and fewer of them can even explain what it means to be Catholic and why that matters.

Young Catholic America, the latest book based on the groundbreaking National Study of Youth and Religion, explores a crucial stage in the life of Catholics. Drawing on in-depth surveys and interviews of...