Gays and lesbians as of 2:15 p.m. local time (9:15 a.m. EST) can now apply for marriage licenses.
Ireland will also recognize same-sex marriages that were legally performed in other jurisdictions. Gays and lesbians who had previously applied for a civil partnership before Monday can change their application to a marriage license without penalty.
“It is a truly joyful and historic moment, not just for lesbian and gay people, their families and friends, but for all Irish people,” said Tiernan Brady of the Gay and Lesbian Equality Network, an Irish advocacy group known by the acronym GLEN, in a statement.
Ireland in May became the first country to extend marriage rights to same-sex couples through a popular vote.
President Michael Higgins in August officially amended the Irish constitution to codify the referendum results. The Irish Presidential Commission on Oct. 29 formally signed a law that extended marriage rights to same-sex couples.
Scotland, England, Wales, France, Spain and the Netherlands are among the European jurisdictions in which same-sex couples can legally marry.
Lawmakers in Northern Ireland earlier this month for the first time voted in favor of marriage rights for same-sex couples. The Democratic Unionist Party, a Protestant party that has the most seats in the Northern Ireland Assembly, used a “petition of concern” to block the motion.
Brady in his statement noted that Ireland extended marriage rights to same-sex couples 22 years after the country decriminalized homosexuality.
A law that allows transgender people to legally change their gender without medical intervention took effect in September.
Ireland is the fourth country to allow trans people to legally change their gender without surgery and other medical interventions. Advocates have nevertheless criticized the law — known as the Gender Recognition Act 2015 — because it does not include intersex people and those who are under the age of 18.