Built on Stilts, the annual dance festival held at the Union Chapel in Oak Bluffs, opened last night to begin its eight day run with a bit of drumming, belly dancing and a group of five-year-olds taking the stage fresh from their yearlong “Stiltshop” choreography class. What’s on the schedule for tonight is anyone’s guess, though, as the show never repeats itself.

Built on Stilts began 15 years ago in the summer of 1997. Cofounders Abby Bender and Anna Luckey had just graduated from Bard College with majors in dance and were looking for a way to show their work. Ms. Luckey invited a group of approximately ten dancers from around Martha’s Vineyard to her home in Vineyard Haven. They hatched a plan to have a dance performance at Union Chapel, pulled it off, and realized it was so much fun they had to do it again.

“The next year we met a few more people and it became a two night thing and it became more diverse. Like we had some belly dancers involved and Kelly Peters was involved and it just grew and grew and grew,” said Abby Bender in an interview with the Gazette at her summer residence in Oak Bluffs on Tuesday.

“I’m someone who likes to take something and make it live to its full potential so I really kind of aggressively went after it and now everybody and their brother wants to be a part of it, which is great. It’s much more varied. It doesn’t feel insular. In some ways I miss the old days where we were all dancing in each other’s pieces but it still feels like a family,” she said.

This year there are fifty-three dance pieces from fifty different choreographers. Many of the pieces are co-choreographed by the dancers. The performers are varied as well. There are children doing pieces choreographed by their dance teachers, young adult dancers putting pieces together because they don’t have other places to show their work, professional dancers who want a noncompetitive environment to show their work, and older men and women who have never lost their passion for movement.

The festival has also gained attention from the off-Island dance communities.

“This year it is easily 50 to 60 per cent visiting artists which is exciting because you’re bringing some really high quality, generally more professional, work to mix in,” said Ms. Bender. “And they all go nuts for it because they’re so jaded. You know they’re in New York or these other places that [are] inundated and [the performers are] not important and out here they are reminded, ‘oh my gosh,’ there are places that love dance.”

Every day before the show a dress rehearsal is held for all of the evening’s performers. There are only two rules concerning content: No nudity, no swearing. What makes each night’s program come together into a cohesive show is an emphasis on the technical elements of the performance. Behind the cues, the lighting, and the music is stage manager Brent Alberghini, who has been with the festival since its second year.

To commemorate the fifteenth-year anniversary of the festival, Mr. Alberghini put together a 15-minute video of footage saved from all the previous years. It will be shown every night before the dance performances.

“It’s about people who kind of can’t help themselves,” said Ms. Bender, speaking of the essence of the festival. “They need to dance and they need to dance for other people. They need to share it. No matter whether they’re five and they love stilts shop (a performance of young children choreographed by Lucia Dillon and Eliza Greene) or they’re seventy-two and can hardly move but they really want to get up there and show that they have this thing that they can’t help themselves from doing.”

“It’s packed in there every night,” added Mr. Alberghini. “There’s like four hundred people in there and that space echoes with sound so when people are cheering it’s like a rock concert which is so different from other dance experiences.”

Added Ms. Bender: “There’s lots of things about it I can’t actually explain. I mean, I know why it’s so great but it’s kind of incredible that you don’t have to convince an audience in the performing arts of something.”

Amazingly enough each performance is absolutely free. This could explain in part why the audiences treat each show as a gift. But that certainly isn’t the main reason. For that one needs look no further than Mr. Alberghini’s anniversary video. At the end there is a montage of the many performers over the years taking their bows. The moment is set to a song to the tune of This Land Is Your Land by Woody Guthrie and sung by a large chorus of young dancers.

“This show is your show, this show is our show, From Circuit avenue to the Cliffs of Gay Head, From the Gay Head Lighthouse to Chappaquiddick, Built On Stilts was made for you and me.”

The Built On Stilts festival runs this week through Sunday, August 14, and next week from Saturday, August 20 to Tuesday, August 23 at Union Chapel in Oak Bluffs. All shows begin at 8 p.m. with a drumming and dance warm-up starting 7:30 p.m. Shows are free.