Half centuries from Neil Rock and David O'Halloran ensured CUS retained the Senior Schools Cup with a seven-wicket win over St Mary's at Angelsea Road.
Chasing 196 to win, O'Halloran made an unbeaten 82, sharing a century opening stand with Rock (72) as they made light of what looked a challenging total.
O'Halloran had earlier taken four wickets as St Mary's posted 195 for 7 - Fionn O'Sullivan top scoring with a superb 82 and captain Oscar O'Brien hitting 43.
A delighted CUS skipper Neil Rock said afterwards: "It's great to win two in a row. We lost a lot of the players from last season so for the young lads to step up was fantastic.
"It was a brilliant effort from David O’Halloran who went out and batted through the whole innings after bowling his spell and taking four wickets.
"We'll now look to make it three in a row next year."
LEINSTER SENIOR SCHOOLS FINAL
At Angelsea Road, St Mary's 195-7 (Fionn O'Sullivan 82, Oscar O'Brien 43 David McCulliffe 23 David O'Halloran 4-37) lost to CUS 196-3 (David O'Halloran 82* Neil Rock 72 Nathan Maguire 17; Peter Masterson 2-32) by 7 wickets.