Same-sex couples in Ireland now truly feel like they are "equal citizens", the head of Marriage Equality has said.
Grainne Healy (right) was speaking as the landmark Marriage Bill 2015 was introduced by Justice Minister Frances Fitzgerald in the Dail.
It paves the way for the first official same-sex unions to take place before the end of the year.
Members of Marriage Equality gathered outside Leinster House before entering the Dail gallery to "witness history unfold".
Ms Healy said it was a "historic day" for the gay community in Ireland.
"This is a momentous occasion, and it's great the minister is going to introduce the legislation today," she told the Herald.
"It's the end of a long journey and for those of us in Marriage Equality, it took us 10 years to get here. It's a wonderful occasion, all the more so because the referendum was such a huge win.
"For so many couples, today is the day when finally they feel they are equal citizens and that their relationships will be recognised."
The bill will go through a number of stages in the Dail and the Seanad, which could take several weeks.
The Marriage Equality Referendum was passed by an overwhelming majority, and the result made Ireland the first country in the world to introduce gay marriage by a popular vote.
The vote was also enthusiastically welcomed by gay and lesbian rights groups across the globe. A legal challenge mounted against the referendum result was shot down by both the High Court and the Court of Appeal.
Ms Fitzgerald said she had been "personally very moved by the sheer exuberant joy and delight of many LGBT people and their friends, families and communities."
She said many who had voted 'no' in the referendum had believed that it was the right decision. "They feared that a treasured institution would change. To those people, I say now that there is nothing to fear," Ms Fitzgerald said.
"Marriage will not be weakened by people who passionately wish to be able to marry.
"Many LGBT people will find this society warmer and more hospitable as a result of the decision made by the people of Ireland," she said.