The Rugby World Cup expanded to 20 teams in 1999. The tournament in Wales was the first to feature 20 nations, up from the 16-team format used in the first three editions.
The expansion came during a major transition for rugby union. The sport had become professional in 1995, and the larger field reflected the tournament's growing international reach. Qualification involved 65 nations, while Wales qualified automatically as host alongside the top teams from the 1995 World Cup.
The new format divided the teams into five pools of four. Because five pool winners could not fill a conventional eight-team quarter-final bracket, the three best runners-up played additional playoff matches to complete the knockout stage. Australia ultimately won the tournament, defeating France in the final.
A common mix-up is 2003, when the 20-team format was already established. The expansion happened in 1999 and remained the standard field size through the 2023 men's World Cup.