 Chenu was invited to be a "peritus", or expert, at the Roman Catholic Second Vatican Council (1962–65) where he was influential in the Pastoral Constitution on the Church in the Modern World ("Gaudium et spes").Chenu was a forerunner of the "ressourcement" in theology that preceded the reforms of Vatican II.Chenu played a large role in the reappropriation of historic theological sources that led to the nouvelle théologie.