PROVIDENCE -- There they were. A few different couples - two who appeared to be in their early 30s and one who was well beyond those years - together on a dance floor that didn't really exist, swinging their partners while a jazz trio played against a backdrop of collected art.

Meanwhile, a large crowd was divided on the entertainment. Some were enthralled. Others didn't seem to notice, casually strolling about with glasses of white wine perched on their fingertips.

Whispers went between everyone - couples, friends and singles who captured most extremes of appearance.

There was one thing going on, and there was no one way to describe the crowd. It's something you just don't see every Friday night. It's a once-a-month-deal. And it's at Rhode Island School of Design.

On the second Friday of each month, the RISD Museum opens its main gallery for a few hours for Music Fridays, an evening of music, cocktails, food and fun. Oh, and to get people interested in art. "It does two things," said Matt Montgomery, the museum's marketing director who developed the social nights. "It gives people evening hours to come to the museum, but also the social aspect that might be more of an enticement for some."

It seems to be working.

January's event was the museum's fourth, and the crowd packed the main gallery - the only space where you're allowed to keep your cocktail. (People did wander around the other areas on their way in or out, something the museum encourages.) The three previous evenings drew between 200 and 300 people to the Benefit Street museum.

It's not a unique concept.

The Museum of Fine Arts in Boston holds FirstFridays, a like-minded food and drink event, the first Friday of every month. Museums in Atlanta, Austin, Texas and Santa Barbara, Calif. - to name only a few - also have found success this way.

But Montgomery knew that. It was kind of the idea.

"I was the first marketing director the museum had," he said. "I realized right away that we did a really good job with family audiences and an older audience. But we seem not to have as strong a demographic in the 25-to-45 age range."

So give them a fun excuse - that's where the food, music and cocktails come in - and maybe they'll stay, or come back, for the art.

"Some people feel you have to have a certain amount of knowledge to visit an art museum and really enjoy it," Montgomery said. "Our idea was really to get that kind of younger, professional, single audience."

If January's event was an indication, they've hit the target, kind of. There were plenty of 20-somethings walking around, but there were just as many slightly older folk mingling among the crowd. Guests are led to the museum's main gallery, which has been converted - without really being changed - into a bar, with a drink situation set up at the far end.

A few tables and chairs have been set up, and food stations that feature hors d'oeuvres from a sponsoring restaurant each month. (Hint: If you do want to sample the food fare, get there early.)

Music Fridays run from 5:30-8:30 p.m. The theory, Montgomery said, is that it is a first stop of the night, a happy hour before heading out.

"I like to go to any type of bar," said Allyson Menzies, 23, of Providence. "If people were more dressed up here, it would be a Gatsby party. I consider myself an artsy type, but I don't think you have to be to come."

A lot of the crowd was from Providence but Montgomery is keeping tabs on outside visitors - via zip codes from sign-in sheets - and says attendance is strong among Massachusetts residents and other out-of-staters.

It's an entry point for people who might not otherwise have been motivated to visit a museum," Montgomery said. "I feel a little charmed, because it started off much stronger than we projected. So far it's been great. I've heard there seems to be a need in Providence for a social nightlife theme that is an alternative to a nightclub or bar that also is fun."

Adam Langlais, 23, of Providence, said his nightlife mostly consists of going to the movies. He wasn't at Music Friday to meet anyone new, just to try out something different.

"And it's nice to look at something different than just a bar," Langlais said. "It's a good crowd and a good energy."

It's also a little bit about the museum itself and particularly about preparing for the opening of the Chase Center next September, which will increase the museum's exhibition space by 10,000 square feet. The new building will include a store and front lobby on North Main Street.

"We knew with that we'll want to have expanded evening hours," Montgomery said. "This is a great way to experiment. Now we know that on Friday nights we could have that. This is something people want. Sometimes you want something to do right after work."

If you go ...

RISD MUSEUM

S2WHATS2: Music Fridays

SWHERE: 224 Benefit St., Providence

WHEN: 5:30 to 8:30 p.m., second Friday of the month (next one is this Friday)

MUSIC: The Cosy Collective, performing live and DJ-remixed improvisational jazz and electronic music

COST: $8 nonmuseum members; $5 members

AGE: Must be 21

MORE INFO: www.risd.edu

MUSEUM OF FINE ARTS

WHAT: MFAFirstFridays

WHERE: 465 Huntington Ave., Boston

WHEN: 5:30 to 9:30 p.m., first Friday of every month (next one is March 7)

MUSIC: Grupo Fantasia

COST: $17 (museum admission); free for museum members

AGE: Must be 21

MORE INFO: www.mfa.org

REBECCA KEISTER can be reached at 508-236-0336 or at rkeister@thesunchronicle.com.