Maxim Hermaniuk took part in the Second Vatican Council as the Ukrainian Catholic Metropolitan of Winnipeg. The extracts from his diaries during the Council published here reveal his particular interest in the debates on the sources of revelation, the unity of the Church and episcopal collegiality. Appointed a member of the Secretariat for Christian Unity, he made an important contribution to discussions on the draft of the decree on the Eastern Churches, on which his advice was much sought. During the council he convened regular meetings of the bishops of the Ukrainian Catholic Church in Canada, and worked hard to make better known the situation of the Ukrainian Catholic Church in Ukraine, forcibly reunited with the Russian Orthodox Church in 1946. Its primate, Metropolitan Josyf Slipyj, was released from Soviet imprisonment in 1963. He arrived in Rome, and features prominently in the diaries. A brief biography of Hermaniuk precedes the extracts, and four appended texts include Hermaniuk's summary of the council's work, pastoral letters issued by the Ukrainian Catholic bishops, and a proposed directory for ecumenical practices. This book, the fifteenth volume in a series of studies commissioned by the Institute of Eastern Christian Studies at Nijmegen in the Netherlands, will be of interest to students both of the council and of the Ukrainian Catholic Church.