He produced an impressive performance in leading Wasps to victory in the Heineken Cup final against Leicester last month.
Wasps centre Fraser Waters produced an immense defensive performance that day, was named man of the match, and is rewarded with an England call-up.
However, Bath lock Danny Grewcock - suspended for the opening two matches - has been left out.
Bristol number eight Dan Ward-Smith and Sale fly-half Charlie Hodgson, who have both been recovering from knee reconstructions, are included.
As is Mike Tindall, who hopes to be fit in time for the World Cup after breaking his leg earlier this season.
Ashton has also included a number of players who impressed on the summer tour to South Africa.
Prop Kevin Yates, hooker Mark Regan and scrum-half Andy Gomarsall all keep their places, while England Saxons youngsters Nick Abendanon and Danny Cipriani have also earned senior calls.
Dallaglio will need to prove he can play a full 80 minutes if he wants to break into the final 30-man World Cup squad.
Wasps enjoy such back-row strength that in the closing weeks of the season he was often being replaced at around the hour mark.
In the Heineken Cup final Dallaglio played 50 minutes before being replaced by James Haskell, who is also in the England squad.
Ashton said: "We know it's been one of the issues. He does bring that to the table. He played well at the end of the season in big games. He's there on merit. I've no reservations about it.
"He has to show he can play 80 minutes of rugby and there's no doubt in the Wasps coaches' minds that he can.
"There are places up for grabs and the World Cup training camp will be used as a training camp as well as a selection camp."
Ashton will have to whittle the squad down to a final 30 on August 14.