Back row forward Oliver Holmes, 17, has agreed a two-year contract extension that will keep him at the Jungle until 2012.
Tigers coach Terry Matterson said: "Ollie has shown a good work ethic and he is very keen to do well and progress. At the moment he is training with the full time players and if he continues to improve he could give himself every chance of breaking into the senior squad next year.
"He has only just turned 17 and his performances in training over the last three weeks have been very impressive."
Holmes played for the Tigers Academy last season after joining the club from local junior club Normanton and he is set to feature in the club's under-20's next year.
Holmes, a Tigers fan as a youngster, said: "I'm really pleased to have been given this opportunity which gives me the chance to make a push for a first team place. I have seen players being given their chance at an early age and that is one of the attractions of being with Cas.
"Hopefully I'll be able to make the break through over the next couple of years but in the meantime I'll be giving it my very best with the under-20's and if an opportunity came along to have a first grade chance, that would be the bonus that I'm aiming for."