Republic of Ireland U21 international midfielder Conor Hourihane has signed his six-month contract with the Blues and a number of other first and second-year pros have agreed to remain at Portman Road. Centre-half Tom Eastman is yet to confirm his intentions, while midfielder David Cawley has been released.
Defender Jack Ainsley and midfielder Jamie Griffiths have also agreed six-month contracts, while Eastman is yet to accept his offer of another half-year at Portman Road. Irish midfielder Cawley is set to leave the club.
Manager Paul Jewell says he hasn't seen enough of many of the young players to give them longer term deals: "They are decent players but I have not seen too much of them in action and I also think there is a comfort zone feel about the place here.
"I don't want to be giving young players a contract and then see them take their foot off the gas.
"I want them from the first day of pre-season to be flying and proving they deserve a longer stay, and hopefully we will be able to do that in December."
Over the weekend, Jewell confirmed that keeper Arran Lee-Barrett had agreed a two-year contract and midfielder Colin Healy, who has undergone a hernia operation today, and defender Troy Brown have agreed one-year deals.
Eastman is now the only one of the 21 players whose contracts are up at the end of June with his future hanging in the balance.
Along with Cawley, Brian Murphy, David Norris, Gareth McAuley, Alan Quinn, Kevin Lisbie, Pablo Couñago, who has not been offered a deal by Crystal Palace, Reggie Lambe, Billy Clark and Ian McLoughlin are leaving the club this summer.
Carlos Edwards triggered an appearance clause on his existing deal and is staying at Town for another season, while Damien Delaney recently put pen to paper on a new contract which will keep him at Portman Road for two or three years depending on the number of games he plays in his second season.
Striker Ronan Murray and midfielder Luke Hyam signed one-year deals last month, while academy duo Cody Cropper and Cormac Burke have been given one-year professional deals while they complete their scholarships next season. Academy first-year left-back Joe Whight has been offered a two-year pro contract.
The only players released by the academy this summer were second years Josh Meekings and Rory McKeown.