Derby have snapped up loan stars Frank Fielding, Jamie Ward and Theo Robinson on permanent deals.
England U21 international goalkeeper Fielding arrives from Blackburn and has penned a three-year contract.
Ward, meanwhile, has agreed a two-year deal with the option of a further year.
Both players have moved to Pride Park for undisclosed fees.
The Rams have also agreed a fee with Championship rivals Millwall for striker Theo Robinson.
He spent three months with Derby this season and will pen a two-year contract on 1st July.
Rams boss Nigel Clough is delighted to have already completed three pieces of transfer business, with the 2010/11 campaign having only come to a close on Saturday.
"We have stated our desire to keep Frank, Jamie and Theo for some time so it is nice to be in a position now where we can confirm they will be part of our future," he said.
"All three of them had been on our radar before they even joined us and we've managed to get three of our long-term targets tied down very early in the summer, which is a massive bonus for us as we see them all as big parts of our future."