75% of the 6,000 strong volunteers will be recruited through rugby clubs in England and Wales, recognising and rewarding those who help to deliver the game week in week out.
England World Cup winner, Lewsey, joined the WRU in October and is championing the volunteer scheme which rewards those already involved at rugby clubs across England and Wales with the chance to be part of Rugby World Cup 2015.
All members of the rugby family, including existing volunteers, players, coaches and officials in Wales, can apply to get involved when the world-class rugby event comes to town by completing the official form via: www.wru.co.uk/eng/thewru/vacancies/volunteering
"Rugby in Wales exists because of the individuals who devote so much passion to the community game in their local clubs." said the RWC 2003 winner and former British and Irish Lion who now heads up the development of rugby in Wales.
"Due to this contribution it is the existing rugby club members who have been given the opportunity to play a key role in the delivery of the Tournament.
"WRU clubs, like those in England, have until April 17 this year to apply to be part of this once-in-a-lifetime opportunity via the WRU website.
"Having experienced first-hand how this Tournament and many others like it play such a pivotal role in inspiring people to take up the sport, it is vital that we capitalise on such an opportunity.
"We all remember the good feeling during the London Olympics. For me it was the army of volunteers who contributed so massively to producing that."
'The Pack' will play a key role in the delivery of World Cup games, taking on a range of roles including transport, meet and greet, accreditation and way-finding which will vary in duration across the tournament.
The WRU's new Head of Rugby will also be looking at encouraging more people to take part in rugby in Wales - keeping them in the game beyond RWC 2015.
Lewsey added: "Our legacy focus will be based on supporting club volunteers, be they team managers, administrators, coaches or officials in order to support the fabric of our game."
The application process for clubs closes on April 17. 'Try Outs' (selection events) will then take place from June to December 2014. Members of 'The Pack' will be confirmed in early 2015.
To volunteer at the Rugby World Cup 2015 visit http://www.wru.co.uk/eng/thewru/vacancies/volunteering