Built on Stilts returns to Union Chapel this week for its annual summer dance residence. The festival was founded 21 years ago and continues to thrive with the spirit of dance, inclusivity and community.

What began as a one-night creative dance festival opened its 20th season this weekend. Built on Stilts continues from August 20 to 23. Admission is free.

Abby Bender never imagined Built on Stilts growing into the eight-night Island phenomenon it is today.

Beginning this Thursday, Union Chapel in Oak Bluffs will be filled with the sounds of dancing feet, rhythmic drumming and thunderous applause as the Island gathers once again for the annual Built on Stilts dance festival.

Young dancers of Stiltshop will be performing at Union Chapel Thursday, the opening night of Built on Stilts dance festival.

For two weekends in August Oak Bluffs goes dancing. The beating of drums begins around 7:30 p.m., beckoning people to the corner of Grove and Narragansett avenues. Inside Union Chapel dancers sway and stretch and leap, warming up to the drumbeats.

Tonight the drums will beat in Union Chapel in Oak Bluffs — calling all dancers and lovers of dance to the 17th annual Built on Stilts festival.

Built on Stilts is a celebration of dance in all its forms. It runs from August 8 to 11 and again from August 17 to 20, and every night is free.

Built on Stilts is the Vineyard’s homegrown dance festival and it takes root this summer from August 8 through the 11 and again from August 17 through the 20 at Union Chapel in Oak Bluffs. Choreographers from Martha’s Vineyard and visiting artists from off-Island join creative forces to bring the performances to life. The program is always free and changes each night. Each night begins with a drum circle starting at 7:30 p.m. The Dance program follows at 8 p.m.

Outside Union Chapel last Saturday evening people lingered on the stairs; little girls doing each other’s makeup and mothers making small talk, all the while keeping an eye on the green doors behind them. At 7:30 p.m. sharp, the doors of the chapel opened and the people streamed inside, running to the closest seat and marking their territory in preparation for this summer’s edition of Built on Stilts.

It all begins with the drum circle. At first it’s just a few folks sitting behind their drums, striking the beat ever so softly. But the scene is being set at Union Chapel in Oak Bluffs and quickly it begins to build as the audience streams in, no need for money or tickets, not on this night.