The Rugby World Cup is an international rugby union competition organised by the International Rugby Board and held every four years since 1987.

The winners are awarded the William Webb Ellis Cup, named after William Webb Ellis, the Rugby School pupil who – according to a popular myth – invented rugby football by picking up the ball during a game. New Zealand are the current holders, having won the 2011 Rugby World Cup in New Zealand. The hosts for 2015 and 2019 will be England and Japan respectively.

Qualifying tournaments were introduced for the second tournament, where eight of the sixteen places were contested in a twenty-four-nation tournament. The inaugural World Cup in 1987, did not involve any qualifying process; instead, the 16 places were automatically filled by seven eligible International Rugby Football Board (IRFB, now, International Rugby Board) member nations, and the rest by invitation.

The current format allows for twelve of the twenty available positions to be filled by automatic qualification, as the teams who finish third or better in the group (pool) stages of the previous tournament enter its successor (where they will be seeded). The qualification system for the remaining eight places is region-based, with Europe and the Americas allocated two qualifying places each, Africa, Asia and Oceania one place each, with the last place determined by a play-off.

A World Cup is a type of sporting competition.

World Cup commonly refers to:

World Cup can also refer to: