[The author provides a summary history and theological survey of the contribution of the Faith and Order movement to the goal of full communion, with special emphasis on the participation of Catholic theologians. He addresses methodological issues and ecclesiological developments. Studies on the sacraments, the apostolic faith, Scripture and Tradition, and a variety of contextual issues have contributed to new irreversible relationships among the churches. Research by theologians of Catholic, Orthodox, Anglican, Evangelical, Pentecostal, and historic Protestant churches have created a unique body of ecumenical literature.]