Late first-half tries from Niall Byrne and Mark Prendergast proved pivotal as St Gerard's overcame the spirited challenge of Roscrea at Templeville Road.
The opening half was marred by a nasty-looking head injury to Gerard's second-row Jack Ryan on 24 minutes, which held up play for 25 minutes.
Ryan would have been delighted with the way his team responded as winger Byrne finished off a fine move for a try on 30 minutes. Tommy Whittle converted and he was on target once again when full-back Prendergast crossed in the final moment of the half.
In the second half Roscrea looked to force their way back into the game and captain Mark Kelly finally touched down four minutes from the end, with Tim Foley converting.
This set up a tantalising finish, but Gerard's stayed composed and held on for victory.
St Gerard's College -- M Prendergast; A Mooney, P Mgane, C Callan, N Byrne; T Whittle, P Kelly; H Gallagher, D King (C Madigan 62) , C Doyle (J Dooley 44); J Ryan (B Fitzpatrick 25), B Fitzpatrick (B Morris-Rowe 19); C Kenny, A Cafferky, J Maguire.
Cistercian College Roscrea -- D Lavelle; R Wharton, F Higgins, H O'Connell, T Carroll; C O'Leary (T Foley 45), C Quinn; J Duggan, J Sweetnam, J McEvoy (R Nereny 43); P Gavin, P Ennis (C Doyle 23); M Kelly, A McDermott, J Foley.
Ref -- C McGowan.