Aeque principaliter ("equally important") is a Latin term used by the Roman Catholic Church to indicate a merger of two or more dioceses in which – to avoid questions of predominance – the dioceses are all given equal importance. Such a merger often followed a merger in persona episcopi.
- Diocese of Atri merged aeque principaliter with the Diocese of Penne (15 March 1252 to 1 July 1949)
- Diocese of Prato united aeque principaliter with Diocese of Pistoia (from 22 September 1653 to 25 January 1954)
- Diocese of Bitonto united aeque principaliter to Diocese of Ruvo (from 27 June 1818 to 30 September 1982)
- Diocese of Cervia united aeque principaliter with the Archdiocese of Ravenna (from 22 February 1947 to 30 September 1986)