The 2011 Rugby World Cup was an international rugby union tournament played in New Zealand from 9 September to 23 October 2011. Each of the 20 competing nations was required to confirm its 30-man squad by 23 August; only players in these squads were eligible to take part in the tournament.
Players could be replaced for medical or compassionate reasons, but they would be unable to return to the squad. Any replacement players had an enforced stand-down period of 48 hours before they could take the field.
Players marked (c) were the nominated captains for their teams. Number of caps and players' ages are indicated as of 9 September 2011, the tournament's opening day.
The tournament was played during the Super Rugby off-season. Players who were released or changed clubs are out-of-contract with their clubs and finished with their 2011 clubs, and in-contract with their national unions and/or future clubs for the 2012 (2011–12 in the Northern Hemisphere) season. Players were listed with their current affiliations as of the opening day of the tournament on 9 September (with some on-going updates during the tournament).
Three squads were made up entirely of players from home-based clubs. Two of these, Australia and New Zealand, had players who signed with overseas clubs for the 2011–12 northern hemisphere season. However, all players on both squads played for clubs within their country, either in Super Rugby or New Zealand's domestic ITM Cup, in the preceding 2011 season. In addition, these players remained under contract with their national unions until the end of the World Cup. The third such squad, France, consists entirely of players under contract with French clubs in both 2010–11 and 2011–12.