DORSET — The knowing laughter was palpable Thursday at the Dorset Playhouse, especially among mothers. The Dorset Theatre Festival is opening its 41st season of professional theater with “Cry It Out,” Molly Smith Metzler’s comedy about young motherhood that is both ridiculously funny and heartrendingly serious. And at Thursday’s preview performance, Dorset’s production delightfully delivered all its facets. Yuppie lawyer Jessie and the earthy hospital clerk Lina are two new mothers who find they are neighbors in a tiny Long Island suburb and find they have much in common. They are both lonely, as the fathers are away all day, and have nobody to talk to. So, being able to monitor their babies from Jessie’s backyard, they find their twice-daily coffee klatches a godsend. Their camaraderie, however, is threatened when a wealthy neighbor, Mitchell, implores them to involve his wife, Adrienne, who seems to be having real trouble with motherhood. The super-professional Adrienne, though, isn't impressed and makes that embarrassingly clear. And they are thrown an even more serious monkey wrench — cold, hard reality. Metzler’s 90-minute play is particularly successful at exploring the subject and laughing about it without demeaning its subjects. Mothers, and fathers, in the audience audibly related with what these characters were talking about and were laughing enthusiastically. That was also due to a most sympathetic production, directed by Marc Masterson, that was well cast, particularly Jessie and Lina. Clea Alsip’s Jessie exuded Midwestern sunniness but was terribly uneasy with the choice of stay-at-home motherhood and her profession. Andrea Syglowski’s Lina was a delightfully earthy urban type, though her South Shore bravado covered some pretty big worries. Key was Syglowski’s wiseacre playing hilariously off Alsip’s “straight man,” all the while seamlessly revealing their depth as individuals and friends. Greg Keller was suitably desperate but sympathetic as Mitchell, though Janie Brookshire, well cast, was a bit monochromatic as Adrienne. However, ratcheting down just a notch would have made all of them funnier. Still, there was no silly shtick, and this was a preview performance — the cast’s first time in front of an audience. This is an excellent cast and the performance was both deeply funny and touching. The physical production was up to Dorset’s usual high standards. David Arsenault’s realistic backyard and background — allowing for one of the show’s surprises — was expertly lit by Michael Giannitti. And the costumes of Sydney Maresca, save for Adrienne’s tacky attire, underscored the characters. Dorset Theatre Festival is opening its season with a surefire success that will hit home for many, who will happily laugh and cry. Dorset Theatre Festival Dorset Theatre Festival presents “Cry It Out,” a comedy by Molly Smith Metzler, June 21-July 14, at the Dorset Playhouse, 104 Cheney Road in Dorset. Single tickets are $30-$58, subscriptions from $156; call 802-867-2223, ext. 101, or go online to www.dorsetheatrefestival.org.