This year's Under 20 squad includes six survivors from 2009 in hooker Jamie George (Saracens), props Shaun Knight (Gloucester Rugby) and Joe Marler (Harlequins), fly half Rory Clegg (Harlequins), wing Will Hurrell (Leicester Tigers) and full back Tom Homer (London Irish), who was the top scorer at last year's tournament in Japan with 68 points.
Also called up is 18-year-old London Wasps wing Christian Wade, who has touched down 19 tries for England in the IRB World Sevens Series this season.
Three players won places after emerging in the latter stages of the Under 20 RBS 6 Nations.
Versatile Saracens back row forward George Kruis came off the bench against Italy and Ireland; Leicester Tigers centre Andrew Forsyth was an instant hit in the wins against Scotland and France; and Stade Francais scrum half Charlie Davies underlined his Top 14 form against France in Saint Nazaire.
England finished second on points difference in the U20 RBS 6 Nations behind the Irish, but with all their Guinness Premiership players available they signed off in style with a record points haul in the 47-33 victory in France.
"The way we finished the Six Nations with some of our attacking play makes it hard not to be enthused and the players not involved at the back end of the tournament - like Gloucester's Freddie Burns and Jonny May - have really bounced back fantastically well. You've got to have players in form."
"The forwards performed consistently well, so that part of selection was fairly straightforward. The backs were a little bit more complicated after guys came in from outside the squad and did well, and other guys have picked up some good game time with their clubs. Overall we've got a really good balance."
The squad will be without one major casualty. Lock James Gaskell (Sale Sharks) appeared in last year's JWC final but has been ruled out by the foot injury that halted his stellar club progress in the Guinness Premiership and Heineken Cup.
"His long term career is the most important thing," said Mapletoft. "We'll miss him as he was an outstanding performer in Japan but we have to get on with it."
Second seeds England are based in Rosario for their three Pool B games, starting with a high profile clash with Argentina at the Estadio El Coloso del Parque on June 5 before facing Ireland (June 9) and France (June 13). The semi final and final rounds take place on June 17 and 20.
"The group will be fascinating with three very difficult matches. In the Six Nations we lost to Ireland, then beat France quite comfortably, and Argentina at home is supposed to be our 'easiest' game! We'll have to be very strong. Whoever wins our group will be really battle-hardened going into the semi finals."
England U20 Junior World Championship squad
Arthur Ellis (London Wasps)
Jamie George (Saracens)
Jamie Gibson (London Irish)
Alex Gray (Newcastle Falcons)
Calum Green (Leicester Tigers)
Lee Imiolek (Sale Sharks)
Shaun Knight (Gloucester Rugby)
George Kruis (Saracens)
Joe Marler (Harlequins)
Charlie Matthews (Harlequins)
Jacob Rowan (Leeds Carnegie)
Mako Vunipola (Bristol Rugby)
Will Welch (Newcastle Falcons)
Jackson Wray (Saracens)
Freddie Burns (Gloucester Rugby)
Tom Casson (Harlequins)
Tom Catterick (Newcastle Falcons)
Rory Clegg (Harlequins)
Charlie Davies (Stade Francais)
Andrew Forsyth (Leicester Tigers)
Sam Harrison (Leicester Tigers)
Tom Homer (London Irish)
Will Hurrell (Leicester Tigers)
Jonny May (Gloucester Rugby)
Sam Smith (Harlequins)
Christian Wade (London Wasps)
Mark Mapletoft, Head Coach
Rob Hunter, Coach
Simon Worsnop, Conditioner
Matt Thombs, Psychologist
Kate Burke, Analyst
Nigel Jones, Doctor
Lesley McBride, Physiotherapist
Gary Edwards, Masseur
Charlotte Gibbons, Manager
Gary Lester, Kit Technician
Martin Johnston, Media Manager