This collection of papers has its origin in the encyclical letter "Ut unum sint (no. 95) and the request of Pope John Paul II to study the question of the Petrine ministry with other Christians with a view to "seeking--"together, of course--"the forms in which this ministry may accomplish a service of love recognized by all concerned." After the promulgation of the encyclical in 1995, the theme of the Petrine ministry in its implications for dialogue with the other churches and ecclesial communities resonated throughout the ecumenical community and in studies, conferences and courses at institutes and research centers, focusing on the theological and historical aspects of the issue. The symposium presented here, organized by the Pontifical Council for Promoting Christian Unity, is aimed at furthering study of the role of the Bishop of Rome in the perspective of the search for Christian unity. Catholic experts and delegates representing a range of Orthodox churches took part in the closed-door symposium at which eight speakers presented papers, dealing with each theme from the Catholic and Orthodox points of view.