With the simplest of plots - straight-laced Kate (Tina Fey) wants a baby, white trash chick Angie (Amy Poehler) is her surrogate, and they feud - Baby Mama gets a lot of mileage out of its 99 minutes. Much of that has to do with the sparkling chemistry between the two leads (who once shared the "Weekend Update" desk on Saturday Night Live), as well as solid, hilarious support from romantic interests Greg Kinnear and Dax Shepard, crazy boss Steve Martin, chatty doorman Romany Malco, concerned sister Maura Tierney, and surrogate agency honcho Sigourney Weaver.

Produced by Lorne Michaels, and with those stars, as well as bit players Will Forte, Fred Armisen and many others, Baby Mama has a distinctly Saturday Night Live feel. Indeed, debut director Michael McCullers is a former staff writer on the show, and penned the second and third Austin Powers films for ex-star Mike Myers, as well as the unfortunate Eddie Griffin vehicle Undercover Brother. But this film suffers none of the episodic nature of the latter, nor the overblown silliness of the former. If anything, it's tonally closer to 30 Rock (Fey's SNL-riff sitcom), which is a very good thing. As light as anything at the pictures, Baby Mama is not dumb - an important distinction - but it wears its intelligence loosely, rarely making fun of Angie's ignorance or pumping up Kate's successes. The film is also something of a safe choice for McCullers, who gets exclusive access to his stars' substantial charm and isn't required to do too much behind the camera, although he does manage a solid, fluid and often hilarious comedy - no small achievement - shrewd enough to lean on its strengths and sidestep its occasional shallowness.