The hierarchy of the Catholic Church has stated that formation of lay teachers is essential for the personal sanctification of the teacher and the apostolic mission of the Church (CCE, 1982, #65) and that “formation must be broadened and kept up to date, on the same level as, and in harmony with, human formation as a whole (CCE, 1982, #62). The research reported in this thesis: (1) explores Catholic Church documents and other literature in order to gain insights into the spirituality of teachers who teach in Catholic schools; (2) identifies experiences of teachers’ daily work in Catholic high schools that nurture and sustain teacher spirituality; (3) explores how the insights revealed can inform the practices of formation for lay teachers in Catholic schools. The demonstrated success of a teacher formation known as The Courage to Teach invited exploration to gain understanding of the principles and practices of formation that could prove helpful for developing formation practices within Australian Catholic Education. The research reported in this thesis included teachers reflecting upon their daily experiences of work and identifying, what one called, “moments of grace” that nourished and sustain teachers’ spirits. These experiences were identified as teachers’ experiences of community and their experiences of making a difference. For Catholic schools to continue to have authenticity, the ongoing formation of lay teachers is essential. This does not mean, as others have said, “adding more water to an already overfull cup” by including formation as one more thing for teachers to do. It means making space and providing the opportunity for teachers to discover the ‘moments of grace’ that providentially fill their day. In conversation with Catholic Scripture and Tradition, these moments of grace will nurture and sustain the vocations of lay teachers in Catholic schools, so that lay teachers will both flourish and “teach with authority” (Mk. 1:22).