Drawing on archival records and firsthand accounts, this work explores the history, theology, and missiology of the International Fellowship of Evangelical Students (IFES). It examines how IFES's commitment to immediacy, mediation, and participation are grounded upon a firm belief in the priesthood of all believers and a missional ecclesiology that presupposes God's involvement in all aspects of life, including the university. It traces the impact of diverse cultures and theologies upon the manifold expressions of mission IFES has engaged, and the role of IFES in extending the presence of God's people in places, and among ideologies, where traditional church structures have limited access. This book is a powerful reminder of the transformative impact created when believers, whether students or otherwise, participate in the missio Dei as faithful and creative witnesses in their own contexts. Bearing relevance for all those interested in a Christian perspective on the university or the theological reverberations of student ministry, it also offers a robust theological framework for understanding the legitimacy of parachurch organizations and lay ministry.