The Roman Catholic Diocese of Honolulu (Diœcesis Honoluluensis) encompasses the entire state of Hawaii and the Johnston Atoll, serving as a suffragan diocese under the metropolitan Archdiocese of San Francisco. Originally established as a prefecture apostolic in 1827 and elevated to a full diocese in 1941, it is spiritually anchored at its mother church, the historic Cathedral Basilica of Our Lady of Peace in downtown Honolulu—celebrated as the oldest cathedral in continuous use in the United States. Under the patronal protection of the Blessed Virgin Mary under the title Malia O Ka Malu (Our Lady Queen of Peace), the diocese is uniquely defined by its rich multicultural heritage and its deep devotion to its local saints, Saint Damien de Veuster and Saint Marianne Cope. The diocese is currently navigating a major historical transition as Bishop-elect Michael T. Castori, S.J.—a Jesuit scholar with extensive ministry experience throughout the South Pacific—prepares for his formal episcopal ordination and installation on July 28, 2026, succeeding Bishop Clarence “Larry” Silva, who shepherd-led the island’s faithful for twenty-one years.