This book carefully explores the claim that young adults (18 to 35) are leaving Catholicism in the United States. According to primary empirical research, many young adults stay and do so living their faith in engaged ways. Most, however, do not do it in the traditional context of the parish. Young adult Catholics are living their faith and spiritual life largely in small faith communities, ecclesial movements, faith-based affinity groups, at home, and through individual practice. The description of research findings is supplemented by commentaries from leaders in evangelization and young adult ministry, from both a theological and a sociological perspective. In a church that is more culturally diverse and increasingly Hispanic, this book offers key insights to better understand the spirituality of young adult Catholics today. Contributors include Mark M. Gray, Michal J. Kramarek, Claudia Avila Cosnahan, Allan Figueroa Deck, SJ, Hosffman Ospino, Darius Villalobos, Patricia Wittberg, SC, and Thomas P. Gaunt, SJ.