Dance theater.

Broadway choreographers are used to making the best of things: Actors who can't move. Scenery that gels in the way. Musical arrangements set to stone. But when choreographer Ken Roberson signed on For Avenue Q, the first musical of the 2003-04 season, he had an obstacle that made all the others look small: Many of his performers had no legs to dance with.

Avenue Q, which became a huge success off Broadway last season and moved into the Golden Theatre during the summer, is about the gorgeous mosaic of people living on the low rent, outer-borough thoroughfare that gives the show its name. In Anna Louizos's evocative set, it's a neighborhood of dilapidated two story townhouses populated by whimsically assorted New Yorkers--immigrants, recent college grads, minorities, a blonde femme fatale named Lucy the Slut, a hairy porn addict named Trekkie Monster, even a former television star who's had a precipitous slide down the economic ladder. Invented by songwriters Robert Lopez and left Marx and playwright Jeff Whitty, the characters of Avenue Q are, for the most part, played by footless, kneeless, thighless, hipless hand puppets designed by Rick Lyon. You got a problem with that?

Well, Roberson did. Here, he says, are some of the things you need to think about when you're choreographing for hand puppets: Is the puppeteer a righty or a left? Can the hands, which are affixed to the wrist in a very specific way, manipulate the puppet's head and arms to achieve the desired effect? Will the movement compromise the puppeteer's control of the puppet?

Theater sophisticates know that dancing puppets are not necessarily a contradiction in terms. Anyone who has ever seen a performance of bunraku, the mesmerizing, resolutely adult puppet theater of Japan, knows the delicacy with which sculptures of wood and cloth can be made to move. But bunraku puppets are full-length, fully articulated dolls, and the puppeteers work in teams to adjust their positions. Roberson's task was to create the illusion of dance numbers with Muppet-y creatures of cloth with only arms and heads.

And the puppets in Avenue Q do seem to dance, moving through space and gesturing in time to the music. Roberson miniaturizes the choreography, and makes a fully extended finger as dramatic as an arabesque. There's even a hot bedroom scene that convinces you that there are legs and groins under the wildly gyrating bedclothes.

To pull off such illusions, Roberson says, he had to humbly learn for himself how the puppeteers do their thing, and then add his ideas to the characters they were working with. The show had been growing in workshops for two years before the creators and director Jason Moore decided to bring in a choreographer.

"I was the new guy," he says, "the foreigner"; it took a while before the puppeteers, a sterling crew of four who act and sing and "dance" more than a dozen roles, learned to trust those ideas. "They were worried that they were going to look like bad puppeteers," Roberson says. Now some of the moves that made their nervous get the biggest response from the show's enthusiastic young audiences.

Young in Broadway terms, that is. At the early preview performance I attended, the crowd was dominated by dating couples in their 20s--not the usual Broadway crowd. It's no accident. Avenue Q speaks very pointedly to their concerns. It begins with a lament that asks, "What do you do with a BA in English?"; then it goes on to look at the torments of first jobs, first apartments, first dates, first loves. One of the songs is called "The Internet Is for Porn"; another proclaims, "I'm Not Wearing Underwear Today"; the famous bedroom scene--with "full puppet nudity," as the posters say--is accompanied by a full-company production number, "You Can Be as Loud as the Hell You Want (When You're Makin' Love)." There are other generational markers as well. Older theatergoers would not find the running joke about '70s child star Gary Coleman particularly hilarious: He now works on Avenue Q as a building superintendent and he's played by a woman in overalls and a tool belt. (He's one of the three characters not played by a puppet--the other two are a pair of comic lovers who invite all their puppet friends to their wedding.)

After a season in which Twyla Tharp came at the Broadway musical via ballet in Movin' Out and Baz Luhrman came at it via opera with La Boheme, it was only a matter of time before someone decided to come at it via Sesame Street. Indeed, when Lopez and Marx first envisioned Avenue Q, they were hoping to make it a TV series--in addition to the three human roles and Lyon's soft-core characters, Avenue Q features animations that occasionally move the action along on screens hung at each side of the stage.

"The cartoon generation finally has its musical," said my husband at intermission. But the fact is, some of our most beloved musicals have been cartoons. Not Gypsy or West Side Story, certainly. But Guys and Dolls? A Funny Thing Happened on the Way to the Forum? The Producers? These are wonderful cartoons punched into three dimensions by human performers. Lopez and Marx are working the trick in reverse.

Sylviane Cold has written about theater for the Boston Phoenix, The Wall Street Journal, Newsday, The New York Times, and other publications.