He was the Australian representative at the Synod of Bishops on Catechesis in 1977 and was the first chairperson of the National Catholic Education Commission from 1974 to 1978, remaining a member until 1988.
[9] As president of the Australian Catholic Bishops' Conference he sought to find ways to meet the Church's challenge of a decline in priestly vocations, including considering married priests:[10] Personally I, and I believe every Bishop, would value very, very highly the gift of celibacy, but I think some would be prepared to look at some relaxation of that discipline if that were to help.Carroll also advocated for the extension of Australian visas for asylum seekers, particularly from Timor Leste.
[7] For over ten years, Carroll sought the creation of a special visa category for the East Timorese asylum seekers, most of whom are active members of the Catholic community and have lived in Australia.
While this request was not approved by the Howard government, it triggered the personal intervention of the Minister for Immigration to grant permanent residency status to the asylum seekers where appropriate.
[11][12] In August 2005, prior to attaining 75 years of age, Carroll submitted his resignation to Benedict XVI,[13] which was accepted the following month,[14] but he continued in the role until his replacement, Mark Coleridge, was appointed in June 2006.
In February 2006, as a result of a public appeal, a scholarship was established to help students attend the Canberra campus of the Australian Catholic University.