 He has lectured and written extensively in the areas of historical theology, ecumenism, and spirituality.He was an official Catholic observer at the World Council of Churches's Conference on Faith and Order in Montreal, 1963, at the General Convention of the Episcopal Church in Denver, CO, 1980, and the delegate of the Catholic Church at the meeting of the Anglican Consultative Council in Panama, 1997.Tavard was best known for his emphatic support of ecumenism, focusing on bridging the gaps between Roman Catholicism and Protestant sects of Christianity as well as between Christianity and Judaism.