The Ancient Order of Hibernians is an Irish Catholic fraternal organization dedicated to preserving Irish culture through festivals, memorials, and civic programs. Its mantra is "Friendship, Unity, and True Christian Charity." AOH members are practicing Roman Catholics of Irish birth, descent, or adoption and are either U.S. citizens or intend to become citizens. 

The first American Division of the Ancient Order of Hibernians was founded in New York City in May 1836 as an extension of the organization formed in Ireland in the eighteenth century to oppose the Orange Order, a Protestant group. The Irish diaspora in the United States believed it needed protection against anti-Irish sentiment, bigotry, and discrimination, and it wanted to consolidate political influence and the preservation of Irish culture and traditions.

The AOH Portland Division was established in November 1877, with forty-four charter members taking the oath of Brotherhood. Between 1850 and 1880, immigrants fleeing the Irish famine comprised one of the largest groups of foreign-born citizens in Portland, and the Portland Division was a way for Irish immigrants and descendants to become active in the Catholic Church. The AOH also helped expand the church’s network of parishes and schools and to ultimately defeat the anti-Catholic Ku Klux Klan and its allies in court. Separate Oregon divisions of the organization were formed in Astoria, Heppner, The Dalles, and Lakeview, and a female auxiliary was started in Portland. 

In 1910, the Portland Division hosted the National Hibernian Convention at the Masonic Temple on Park Ave. (now part of the Portland Art Museum), where fifteen hundred delegates gathered in what was reportedly one of the most significant gatherings of Irish men and women in America at the time. In 1914, following the convention’s success, Hibernian Hall was built on Northeast Russell Street. The Depression took its toll on the organization, and the AOH faded from Portland civic life. The building was turned over to the Catholic Archdiocese of Portland in 1936 and remained in almost constant use as an athletic and meeting hall and as a daycare. in 2004, the hall was purchased and refurbished into the Wonder Ballroom music venue. Hibernian Hall was listed on the National Register of Historic Places in 2005. 

By 1933, membership had dropped to about thirty members, and the AOH Portland Division was dormant. It was revived in June 1997 with the 150-year commemoration of the Irish potato famine, An Gorta Mór, which had caused a million Irish to die from starvation between 1845 and 1851 and more than two million to leave Ireland. The commemoration, initiated by Dublin immigrant David O’Longaigh, was held at Hibernian Hall. AOH’s National President, Edward J. Wallace, agreed to the observance on the condition that O’Longaigh re-establish and lead the AOH in Oregon. On June 1, 1997, about six hundred people attended the event, showcasing Irish history in Oregon with music and dancing, storytelling, and arts and crafts. O’Longaigh incorporated AOH and re-established the Portland Division in February 1998. 

In 2006, the Portland Division of the AOH, the Roman Catholic Archdiocese of Portland, and Mount Calvary Cemetery commissioned a replica of the ninth-century Scriptures of the Clonmacnoise cross in Offaly, Ireland, as a memorial to the Irish who immigrated to the United States during the Great Famine of 1845–1851. The seven-ton, fourteen-foot-high cross was sculpted by Brenden McCloin and hand-carved from Irish sandstone in much the same fashion as the original had been. 

In 2022, there were 27,000 dues-paying AOH members in the United States and 50 active dues-paying members of the Portland Division, the only AOH division in Oregon.