Flanker Calum Clark (Leeds Carnegie), hooker James Clark (London Irish), centre Luke Eves (Bristol Rugby), fly half Rob Miller (Newcastle Falcons), flanker/lock Courtney Lawes (Northampton Saints), wings Charlie Sharples (Gloucester Rugby) and Seb Stegmann (Harlequins), and scrum half Ben Youngs (Leicester Tigers) all bring previous Junior World Championship experience to England's bid for victory in Tokyo on June 21.
And one player earns a call-up from outside the 32-man Elite Player Squad drawn up in January. Harlequins wing George Lowe seized his opportunity with three tries in three RBS Under 20 Six Nations appearances to win his place on the plane to Japan.
Fourteen clubs are represented with Gloucester (five) and Harlequins (four) providing the largest contingent in the JWC squad selected by Mapletoft and fellow coach Martin Haag.
"This is an exciting squad to be involved with and we have the talent, experience and ambition in the group to mount a really strong challenge for the world title in Japan this summer," said Mapletoft.
"Everyone in the squad for this tournament has made an impact in the Premiership this season or on dual-registration with National League clubs and that made selecting a squad of 26 a very tough task. There were close calls and there will be some very disappointed players out there.
"That said, it's a pleasure to welcome back the likes of Courtney Lawes, Graham Kitchener, Ben Youngs and Charlie Sharples, who all only appeared once or twice for us in the Six Nations before getting a lot of exposure for their clubs, and to have Dave Lewis returning after injury.
"We gave debuts to 26 players and used 37 in total during the Six Nations, and while that provided some challenges it gave us the chance to look closely at a lot of players and for the likes of George Lowe to take the chance that was on offer."
Stuart Lancaster, RFU Head of Elite Player Development and England Saxons Coach, added:
"It's essential that our players get the invaluable experience they receive playing in the 2009 IRB World Junior Championships.
"The benefits to their development are massive, as was proved last year with players like Alex Corbiserio, Joe Simpson, Alex Goode, Noah Cato and Jordan Turner-Hall all playing their part in helping England reach their first age group representative final.
"Each of these players has been part of the England Saxons squad this year and has played a significant part for their clubs in the Guinness Premiership, which underlines that the player pathway for our young players, who come through the Academy system we run with the clubs, is there and it is working."
"It's vital that trend continues and the players taking part in the 2009 World Junior Championships have a great opportunity to be part of that."
The second seeds start the tournament with Pool B games against hosts Japan on June 5 (7pm), Scotland on June 9 (5pm) and Samoa on June 13 (1pm), all at the Prince Chichibu Stadium in Tokyo. The semi-finals and finals are scheduled for June 17 and June 21.
England prepare with a warm-up game against Loughborough University on May 13, part of a week-long training camp in the Midlands, before departing for Japan on May 27.
England Under 20 Junior World Championship Squad:
Bob Baker (London Wasps)
Calum Clark (Leeds Carnegie)
James Clark (London Irish)
Carl Fearns (Sale Sharks)
James Gaskell (Sale Sharks)
Jamie George (Saracens)
Graham Kitchener (Worcester Warriors)
Shaun Knight (Gloucester Rugby)
Courtney Lawes (Northampton Saints)
Joe Marler (Harlequins)
Ben Moon (Exeter Chiefs)
Josh Ovens (Bath Rugby)
Dan Williams (Gloucester Rugby)
Chris York (Harlequins)
Tom Casson (Saracens)
Rory Clegg (Newcastle Falcons)
Luke Eves (Bristol Rugby)
Tom Homer London Irish)
Dave Lewis (Gloucester Rugby)
George Lowe (Harlequins)
Rob Miller (Newcastle Falcons)
Charlie Sharples (Gloucester Rugby)
Seb Stegmann (Harlequins)
Henry Trinder (Gloucester Rugby)
Greig Tonks (Leicester Tigers)
Ben Youngs (Leicester Tigers)