School chaplaincy in Australia is highly contentious. The federal government funds a chaplaincy programme in Australia's secular public schools, which, combined with the declining influence of institutional Christianity, places Christian chaplains at the nexus of debates on the public role of religion. Yet little is known about how these chaplains integrate their religious convictions with their role. This article draws on 12 interviews with Christian chaplains, and asks: (1) how do these chaplains understand their faith within their role?; (2) how do they practice their faith through their role; and (3) how do they negotiate the ban on 'proselytising'? This article finds that chaplains see their work as a call from God that enables a deep sense of purpose, and is also aimed at young people's empowerment. They practically express their faith through care, bridging school and Christian communities, and prayer. Last, they practice conversations about faith, described as 'dialogical evangelism'. Given the lack of studies of chaplaincy practice in secular contexts, this article is significant for its empirical depth, and discussion of controversial topics. It concludes by examining the significance of these findings for policy makers, and for wider debates about the interaction between religious people and secular institutions.