Advice to casting agents: the camera loves dancers--tomorrow's screen idol may be in a Broadway ensemble right now.

Idly flipping through the cable channels the other night, I found myself lingering at the sweetly sentimental image of James Cagney proposing marriage to Joan Leslie in Yankee Doodle Dandy. It's a movie I've loved since I was a girl, before I knew or cared that it was a portrait--idealized, of course, for a less cynical time-of George M. Cohan, one of Broadway's seminal figures.

Cohan was a pioneer--a composer, performer, and producer--whose rousing shows helped bridge the gap between vaudeville entertainments and musical comedies. But watching Cagney impersonating Cohan's cocky walk and strutting style of dance for the first time in years, I found myself thinking about how rare it is these days for a Broadway dancer--or, for that matter, a ballet dancer--to become a big-deal movie star. Cagney's Broadway career ended in 1930, but like many dancers before and since, he took his training with him when he went Hollywood.

There have been plenty of dance stars in the movies, of course. And Cagney wasn't alone in moving from dance roles to drama. For every Fred Astaire or Gene Kelly, whose movies kept them dancing, there's a Leslie Garon or a Christopher Walken, who turned in dance shoes for straight acting roles early on and never looked back. Still, dancers bring a special something to the screen, even when they're not working in musicals. A quick mental survey turns up many examples.

In the independent movie Things to Do in Denver When You're Dead, Walken plays a paraplegic crime boss who can't move anything but his head. You would think such a role would prove daunting for an ex-dancer whose eloquent body language has served him often and well. But armed with a pair of shifty eyes, a panoply of grins and half-smiles and a dazzling array of nods, jerks, and swivels, Walken's head steals the movie from the other performers, who are busy acting with their whole bodies.

In Le Divorce, Caron portrays a very proper French matron whose son rather improperly abandons his pregnant American wife. Sitting stock-still in her bedroom, regal in a yellow satin dressing gown, Caron conveys hauteur, distress, and pique with the subtlest tilts of her head as she quietly discusses the bad behavior of husbands as a breed. It isn't that she's not able to do more to milk the scene; it's that she doesn't need to. Like the ballerina watching quietly from the sidelines as the peasants dance, Caron concentrates her self, letting the audience come to her.

It's a trick you can see in another one-time ballet dancer, Audrey Hepburn, in Breakfast at Tiffany's. The familiar, iconic image of Holly Golightly in her sunglasses, musing on the sidewalk in front of the jewelry store with a cup of coffee in one hand and a pastry in the other, is utterly static. Yet Hepburn's vitality--the vitality that animates all dancers, whether or not they are in motion--is enough.

Another former dancer, Buddy Ebsen, has a brief, sad turn in the movie as Doc Golighfly, Holly's estranged husband. Ebsen was originally a hoofer, not a ballet dancer--you can get a glimpse of his stylish, loosey-goosey tapping in early movie musicals like Born to Dance. By the time he was cast in the now classic sitcom The Beverly Hillbillies, he was long past his dancing days. Yet you can see him using the same strategy employed by Hepburn and Caron in their films. He was inarguably the central focus of the series, its fulcrum--even though he spent so much of his time just standing around in the kitchen or the living room with his hands in his pockets, as Irene Ryan or Max Baer or Donna Douglas had conniptions over some foolishness or other.

Dancers, it seems, are especially good at making us watch them as they watch others. Take Patrick Swayze, a Calcutta doctor in City of Joy. When there's actual action, it seems somehow less compelling than when he's just looking at the vibrant life all around him.

The obvious conclusion-that dancers make good screen actors because of the lightness and grace with which they move, because they are so visibly at home in their bodies and so practiced at using them--seems to be a little beside the point.

Dancing also teaches you how to be legible, no matter what you're doing. And if you can make things interesting while you're standing still, imagine how overpowering you'll be when you start to move. Movie directors and casting agents looking for performers who can keep the camera interested over decades might want to skip the off-Broadway workshops and the drama school productions and check out the ensemble of a Broadway musical instead.

Sylviane Gold has written about theater for Newsday and The New York Times.