At first glance (or at first sight of the theatrical trailer), "The Family Stone" would appear to be one of those manipulative, middle-of-the-road, stringently conventional comedies that give female-targeted films a bad name. But, like the recent "In Her Shoes," "The Family Stone" surprises by not going to those broad cornball places. Written and directed by Thomas Bezucha, the picture wavers smoothly between humor that earns some big laughs from its truthfulness and drama that knows how to tug at the viewer's heartstrings without needing to break out an overbearing one hundred-piece orchestra.

With Christmas just days away, oldest child Everett Stone (Dermot Mulroney) brings his girlfriend, Meredith Morton (Sarah Jessica Parker), to his New England hometown to meet his family for the first time. The Stones, progressive in thought but set in their ways, include parents Sybil (Diane Keaton) and Kelly (Craig T. Nelson), easygoing married daughter Susannah (Elizabeth Reaser), openly gay and deaf son Thad (Tyrone Giordano), opinionated younger daughter Amy (Rachel McAdams), and wild and freewheeling son Ben (Luke Wilson). The introduction of a new person into the familial equation starts off rockily and goes downhill from there, with the uptight and more inward Meredith clashing instantly with the Stones. As Everett tiptoes around asking mother Sybil for the family engagement ring she has always promised him, it becomes clear to Sybil and Amy that his chosen fiancée isn't right for him. Meanwhile, Meredith falls deeper in over her head as she makes an effort to please the family, eventually calling in her own sister, Julie (Claire Danes), for support.

Writer-director Thomas Bezucha knows the tricky, complicated dynamic of families, and keys into that in "The Family Stone" in spontaneous ways that strike rich, funny and poignant notes. The Stones, in all of their messy, territorial, but unconditionally loving glory, could stand for any average, like-minded family. It isn't that Meredith is a spiteful or unbearable person, but her dysfunctions are so different from the Stones' dysfunctions that they might as well be living on different planets. Because of this, Sybil can't help but involve herself in Everett's future; she knows he and Meredith aren't right for each other, or, at least, can't admit that they are.

A whole lot of tart comic mileage is made in the story's first half, with Meredith hopelessly trying to be welcomed into the family and hitting road blocks with every attempt. When playing a game of charades, for example, Meredith's hand gesture is mistaken for a racial inference. Her lack of comfort in staying in the same room with Everett while at his parent's house leads her to taking Amy's bedroom and pushing her out to the couch to sleep, although this is not her intention. And when dinner conversation turns to Thad's sexual orientation and Meredith questions Sybil's declaration that she was hoping for a gay son, the scene turns ugly real quick. Most of the laughs in "The Family Stone" hit home because they are so cringe-inducing—not from being raunchy, but because of the mortifying authenticity and nuances found in its portrait of a woman forced to interact in close quarters with an extended family as different from her as night and day.

To be fair, Meredith doesn't exactly start the film out warming the audience's heart, either. With her hair pulled tightly back in a bun, her attire as drab as it is spotless, plagued with a throat-clearing tic every time she gets nervous, austere in her emotions, and about the direct opposite of laid back, Meredith is in desperate need of loosening up. The treat in the screenplay, therefore, is that for all of their shortcoming and flaws, Meredith and each of the Stone family members grow throughout into full-rounded, sympathetic, multifaceted people. When Meredith finally lets her "freak flag fly" and ends up getting drunk and uninhibited while out at a bar with Ben, it is exceptionally endearing to see her finally for who she really is: beautifully, clumsily, unashamedly human.

After six years on HBO's groundbreaking "Sex and the City," Sarah Jessica Parker (1999's "Dudley Do-Right") slides into her first lead film role in the better part of a decade as a stronger actress of depth, character and ace comic timing. She stands out from the rest of the cast because of her odd-man-out part, but also because of Parker's innate exuberance as she finds the complexity and vulnerability in Meredith that makes her the picture's most fascinating character.

The rest of the actors are lovely too; there isn't a weak performance to be had. Diane Keaton follows up her Oscar-nominated turn in 2003's "Something's Gotta Give" as opinionated Stone matriarch Sybil, garnering real pathos in her portrayal of a woman harboring a secret from her family in an attempt to spare them the pain it will cause those she loves most. Craig T. Nelson (2000's "The Skulls") does his best screen work in years as even-keeled, understanding father Kelly.

Rachel McAdams (2005's "Red Eye") continues her rise toward become the next major movie star with her tricky role as Amy, arguably the least likable member of the Stone family, but also one that is never one-dimensional and, by the end, is shown to have a bigger heart than she lets on. As brothers Everett and Ben, Dermot Mulroney (2005's "The Wedding Date") and Luke Wilson (2003's "Old School") are amiable as the love interests of the film, but as they relate to the rest of their family members, they also get a few scenes where they are dramatically affecting on a deeper level. Only the fine Claire Danes (2005's "Shopgirl"), as Meredith's visiting sister, Julie, is left with little to do. When she asks several times throughout why she is even there, the viewer is forced to broach the same question; save for a romantic subplot that is fairly featherweight, Danes' role is superfluous.

With "The Family Stone" turning an eye toward a fatal disease that one of the characters has, there is a first moment of apprehension on the viewer's part that turns out to be unfounded. As befits the reality director Thomas Bezucha brings to all of his movie's story points, this subplot stays low-key and unobtrusive. Free of sappy melodrama and overwrought emotions, Bezucha deals in a matter-of-fact way with how a tight-knit family might react to learn that one of their own is dying, and wrings some genuinely touching moments from it. In the end, the film balances being airy and entertaining and silly and honest and biting and a little sad without any one element overshadowing the others. And the final scene, signifying how families press on and endure following a personal loss, finding comfort within memories, is powerful in its delicacy. With intelligence and unforced spirit to spare, "The Family Stone" is that rare widely commercial motion picture worth embracing.