Tripp (Matthew McConaughey), left, a thirtysomething man who still lives with his parents, falls in love with Paula (Sarah Jessica Parker), the woman of his dreams and begins to suspect she has been hired by his parents as a way to get him out of the house in Paramount Pictures' "Failure to Launch."

In the badly titled "Failure to Launch," Matthew McConaughey and Sarah Jessica Parker perform with the calculated congeniality of talk-show guests.

That turns out to be the ideal approach for this material. "Failure to Launch" winds up being almost as congenial as it is calculated. It's kept afloat by McConaughey's buoyant performance and, to a lesser degree, by Parker's more labored effervescence.

The screenplay obeys virtually every comic formula. Two opposites-attract singles find love. Some boyhood friends refuse to grow up. Even the cuddliest animals are not as innocent as they look. A misanthropic roommate helps the heroine seem even more — here's that word again — congenial. A romantic reconciliation occurs in the most public of circumstances. And, of course, there's a precocious child who speaks words of wisdom to the doltish adults.

Under Tom Dey's direction, a perverse form of symmetry is at work here, and the abundant stereotypes seem like old acquaintances you can enjoy for a couple of hours.

McConaughey plays Tripp, a 35-year-old macho man who still lives with his parents. He has his own reasons for maintaining this arrangement, but Mom and Pop, played by Kathy Bates and Terry Bradshaw, long for the freedom of empty nesters. Eventually they hire Paula (Parker), whose peculiar profession is that of an unlikely therapist.

Paula's specialty is to make the adult male fall so heedlessly in love with her that he'll willingly liberate himself from his childhood homestead. If that sounds like a dirty trick to you, you're not alone. Tripp gets furious when he discovers her agenda.

The two stars manage to make their characters more appealing than they have any right to be. Among the large supporting cast, Zooey Deschanel scores the most laughs as Paula's sardonic roommate, who would love to kill the mockingbird that keeps her from getting a solid night's sleep. Bates also handles sarcasm deftly.

Bradshaw delivers a pleasantly crusty performance. But in one ill-advised scene he bares his backside for all to behold. He should have objected. Loudly.

"Failure to Launch" doesn't reach the zany plateau of "Wedding Crashers" or "The 40-Year-Old Virgin." But it should please viewers who made McConaughey's "How to Lose a Guy in 10 Days" an unexpected hit three years ago.