In the 19th century, there was considerable Irish immigration to Puerto Rico, for a number of reasons.

In Ireland during the 1840s, potato fungus created the Irish Potato Famine which killed nearly one million Irishmen and created nearly two million refugees. These refugees went to the United States, Australia, Canada, New Zealand, and, among other places, the Caribbean. One of the islands that many Irishmen emigrated to in large numbers was Puerto Rico. Being a Spanish colony, the island had a primarily Catholic population, as opposed to the Protestant majorities of most of the British Empire at the time.

The famine in Ireland came at a time when concern in Spain was growing about the possibility of rebellion in her Caribbean possessions. In the decades prior, Spain had lost almost the entirety of her territory in South and Central America, and sought measures of preventing a repeat of this in the Caribbean. It was decided that an influx of Catholic immigrants (primarily from Ireland, Italy and France) would provide a loyal base for the Crown, and appeals were made to encourage immigration.

The diaspora following the famine was not the first instance of emigration from Ireland; during the gradual English conquest of Ireland from the 12th to 17th centuries many Irishmen abandoned the country for Catholic Europe. Though some found themselves in the Spanish empire overseas (a handful even rose to administrative positions in Cuba), there was no significant Irish community in the Caribbean outside Montserrat and Barbados until the 19th century.

Today, the Irish element of Puerto Rico is very much in evidence. Surnames such as O'Neill, Murphy and Sullivan are common. Examples of famous Irish-Puerto Ricans are women's rights activist Ana María O'Neill and Kenneth McClintock who was elected President the Puerto Rican Senate in 2004.

See also

• Immigration
• Irish diaspora
• List of famous Puerto Ricans