Fifty or sixty years ago, these now-commonplace elements of American church life were regularly found in youth groups but rarely in worship services and adult activities. What happened? Beginning in the 1930s and ’40s, Christian teenagers and youth leaders staged a quiet revolution in American church life that led to what can properly be called the juvenilization of American Christianity. Juvenilization is the process by which the religious beliefs, practices, and developmental characteristics of adolescents become accepted as appropriate for adults. It began with the praiseworthy goal of adapting the faith to appeal to the young, which in fact revitalized American Christianity. But it has sometimes ended with both youth and adults embracing immature versions of the faith. In any case, white evangelicals led the way.