Keith Andrews's ninth goal of the season gave Ipswich Town their second consecutive win this afternoon.
The Irishman, who is on loan from Blackburn Rovers, is the Tractor Boys' top scorer this campaign but has recently agreed a January move to Swansea City.
Visiting Derby started the brighter of the two sides and stand-in keeper Arran Lee-Barrett made some impressive early saves to keep the scores level.
Paul Jewell's side started to impose themselves towards the end of the half and took the lead straight after the break.
Aaron Cresswell swung the ball over from the left and Frank Fielding mishandled before Andrews headed towards goal. There was confusion as to whether it had been given as the referee originally appeared not to, but was told by his linesman to award the goal.
The home side saw out the game with ease, with Derby offering very little in reply.
Ipswich move up one place to 19th with the victory while Derby drop to 16th.