Teenage batsman Aneurin Donald has signed a three-year deal that keeps him at Glamorgan until the end of the 2018 season.
And seam bowler Dewi Penrhyn Jones, 21, has agreed a one-year contract after taking five wickets in their final two 2015 Championship matches.
England Under-19 captain Donald hit 98 in the final match of the season against Gloucestershire.
"I've learnt a lot from being in the first team dressing room," said Donald.
"Now I've got a great opportunity to develop my game and focus on my cricket."
Donald is spending the winter at the Darren Lehmann Cricket Academy in Adelaide, Australia.
There are also one-year development contracts for batsman Jeremy Lawlor and fellow Cardiff MCCU product Jack Murphy, a fast bowler who was affected by injury in 2015.
Chief executive Hugh Morris said: "These home-grown cricket talents are all capable of succeeding and achieving honours for Glamorgan."
The county has also recently announced a contract extension for batsman Chris Cooke until 2018.