This study investigates the relationship between Catholic teachers' faith and their school commitment in Catholic high schools. A national sample of 751 teachers from 39 Catholic high schools in 15 archdioceses in the United States participated in a self-administered website survey. Data were analyzed using descriptive statistics and the Pearson correlation. The findings of this study show that there are significant relationships between the four dimensions of Catholic teachers' faith (belief, intimacy with God, action, and a living faith) and the four dimensions of school commitment (commitment to mission, commitment to the school, commitment to teaching, and commitment to students). Among the four dimensions of Catholic faith, a living faith was most influential in all the four dimensions of teacher commitment. Among the four dimensions of teacher commitment, commitment to mission was most strongly connected with all four dimensions of faith. The findings of this study strongly suggest that Catholic teachers' living faith, placed in the center of intrinsic motivation for their school lives and activities, needs to be acknowledged as a critical predictor of teacher commitment within Catholic high schools. (Contains 7 tables.)