Clontarf skipper Una Raymond-Hoey scored 150 as her team beat defending champions Leinster in their 50-over game at Castle Avenue.
The Irish international hit 13 boundaries in her 138-ball innings, helping her side to an imposing 325 for 5.
The 22 year-old added 71 for the first wicket with Aoife Brennan (34) and a superb 157 in 123 balls with coach Izzy Joyce, who made 84.
Two wickets for Molly Butler (2-16) saw Leinster struggling on 98 for 5 after 20 overs when play was halted - Clontarf winning comfortably on DLS.
"It was great to get our second 50 over win of the season yesterday," said Una Raymond-Hoey afterwards.
"We really struggled in the longer format last year so to be showing signs of improvement in this area is really positive for us as a team.
"Our two 50 overs guest players (Jane Maguire and Cliodhna O'Reardon) have really helped bolster the side and our bowlers are becoming better at managing longer spells.
"The game ended up being affected by rain, but I think 324 is a total I would have been confident with us defending - especially against a Leinster side missing Laura Delany and Amy Kenealy.
"From a personal perspective, I've had a few low scores so far this season and have been trying to work on a few different things at training so to be able to contribute yesterday alongside Izzy Joyce to a good team win was really pleasing."