The Ecumenical Institute for Advanced Theological Research at Tantur owes its origin to a convergence of ideas, personalities and events which we conveniently summarize by reference to the Second Vatican Council. The central mission of the institute at its founding, which has undergone some healthy review and revision at various stages since that beginning, emerged from the extraordinary experience of that extended encounter in Rome. This volume reflects this history and the challanges of the future of the ecumenical adventure.