After serving on the Canadian Bishops' Commission for Relations with Associations of Clergy, Consecrated Life and Laity, as a member of the CCCB Theology Commission known as the Doctrine Commission, its Commission on Social Communications, several terms on the Permanent Council (including since 2015 as representative of the Bishops of Ontario) and earlier as co-chair of the national Anglican-Roman Catholic dialogue, Prendergast is, since October 2014, a member of the CCCB's Episcopal Liaison Committee to the Canadian Catholic Organization for Development and Peace.