The International Rugby Board (IRB) is the world governing and law-making body for the sport of rugby union, and previously for rugby football . It was founded in 1886 as the International Rugby Football Board (IRFB) by the unions of Scotland, Wales and Ireland. England originally refused to take part, but in 1890, it became the first non-founding union to become a member. The International Rugby Football Board changed its name to the International Rugby Board in 1997. The IRB's headquarters are located in Dublin, Ireland.

The IRB has 96 full member Unions, 19 Associate members and six Regional Associations, with the 96 full member unions meeting bi-annually and Regional Associations organising regular meetings. The IRB organises some of the sport's international competitions, with the Rugby World Cup (occurring every four years) being the most popular and highest profit competition for the IRB, as seen by the £81.8 million (approximately $USD150 million, €118 million, ¥17300 million) gross commercial income of the 2003 tournament. The IRB also provides money to smaller nations, such as the Pacific Islands teams, who are unable to generate their own income.