Comedy often works better when actors opt to play things straight. That's a lesson Christopher Guest (Waiting for Guffman and Best in Show) long ago learned.

In "mockumentary" after "mockumentary" (beginning with his work in This is Spinal Tap), Guest has proven that he has a perfect ear for dialogue and a great eye for the peculiarities of human behavior, particularly when it's obsessive.

A Mighty Wind allows Guest to tackle (or is it "tickle") the world of folk music, turning parodic cartwheels around a nifty premise: When folk impresario Irving Steinbloom passes away, his son Jonathan (Bob Balaban) stages a memorial concert featuring some of Irving's favorite groups.

There's Mitch & Mickey (Eugene Levy and Catherine O'Hara), The Folksmen (Guest, Michael McKean and Harry Shearer) and The New Main Street Singers (a group that includes John Michael Higgins, Jane Lynch and Parker Posey).

If you're a Guest fan (and you should be) you'll recognize the cast, composed of the usual suspects who populate Guest's movies.

It's fair to say they're all in fine form, in faux interviews and when performing their songs. Yes, it's really them singing.

The lyrics (particularly of the title song) can be funny, but the real humor lies in the way Guest perfectly replicates the bland dedication of this part of the folk scene, '60s performers who lobbied hard for commercial success and then faded into well-earned obscurity.

I was a little disappointed that Guest avoided the heavy hitters of folk. You'll find no Dylanesque figures here and no traces of folk's political agenda. Still, the movie's comic chords mostly vibrate with laughter.

Besides, there's something completely engrossing about the thoroughness of the improvisational skills on display - from the manic good spirits of Higgins and Lynch, a couple who founded a new religion based on color worship, to the crass cluelessness of Fred Willard, this time playing a promoter.

Guest, who played bluegrass for real, knows his way around this turf and some of the improvisational goodies delivered by his cast are priceless.

You'll find a stunning parody of a publicist from Jennifer Coolidge. As the depressed Mitch, co-writer Eugene Levy creates a portrait of a man whose brain quakes with tremors from a long-ago nervous breakdown.

It's possible Levy burrowed a little too deeply into this role, sometimes losing sight of laughs.

Levy and O'Hara play at least one song straight, but the comic intelligence runs deep in every scene, manifesting in the costumes and perfectly reproduced album covers.

At this point, a bit of ranking may be necessary. I found both Waiting for Guffman (my favorite) and Best in Show to be funnier.

Not every improvisational bit proves as imaginative as you'd like. Lynch's goody-goody character rather predictably informs us of an early career in porn, for example.

But if the comedy isn't always firing on all cylinders, enough of it works to make A Mighty Wind a worthy entry into Guest's growing gallery of movies that prove far more interesting than the worlds at which they're so brilliantly poking fun.

Robert Denerstein is the film critic. (303) 892-5424 or e-mail him at: denersteinb@ RockyMountainNews.com