The Plenary Councils of Baltimore were three national meetings of Catholic bishops in the United States in 1852, 1866 and 1884 in Baltimore, Maryland.

During the early history of the Roman Catholic Church in the United States all of the dioceses were part of one ecclesiastical province under the Archbishop of Baltimore. This being the case, governance of the American church was carried out by provincial councils held in Baltimore. As the church grew and was divided into multiple provinces, it became necessary for a national (or plenary) council of the bishops of the United States to meet to foster common discipline.

The fathers of the Seventh Provincial Council of Baltimore requested the Holy See to sanction the holding of a plenary council. The petition was granted and the pope appointed Archbishop Francis Kenrick of Baltimore as Apostolic Delegate to convene and preside over the council.