“Everyone can see we’re together as we walk on by,” sang a roomful of campers and counselors at Camp Jabberwocky in Vineyard Haven Wednesday morning, as a live band played. The stage in the camp studio was packed with people singing and dancing to the funky Sister Sledge tune We Are Family.

The group was rehearsing for this year’s camp play, Sister Act, coming up this weekend. In longstanding camp tradition, the Whoopi Goldberg comedy has been reframed to take place in the Jabberwocky world.

“Welcome to Camp Jesuswocky,” announced a beaming, barefoot Johanna (Jojo) Romero de Slavy, the camp’s co-director, who is also co-directing the play with counselor Mike Léon.

Playing Mother Superior, camper Faith Carter laid down the rules of the convent where some showgirls on the run are sheltering from the mob. There are just three rules at Camp Jesuswocky, she said: poverty, obedience and . . . chastity.

“Whoa, whoa, whoa, that’s gonna be a deal breaker!” said camper Susan Harrington, in the Goldberg role. “We just want to party!”

Ms. Harrington — who reached an international audience in the 1999 documentary How’s Your News and is a regular performer in the annual play — also gets to unleash a bloodcurdling stage scream during the show.

A beloved Vineyard summer institution that plays to packed houses, the Jabberwocky play always has comic dialogue, fast action, song and dance numbers and enough smiles to last till the next summer.

At Wednesday’s rehearsal, the camp actors—many with their individual counselors close at hand—danced and sang, several taking center stage for a star turn.

Campers in wheelchairs spun gracefully, holding a counselor’s hand, or pumped arms as a dancing counselor pulled them into a wheelie. Other campers sashayed across the stage or boogied down front.

Along with We Are Family, the cast rehearsed an action scene to music from Mission: Impossible, and a solo version of Bobby Brown’s My Prerogative sung by camper Stefanie Sacks with dancing by the cast.

Ms. Sacks was nervous about remembering the lyrics, but Mr. Léon assured her she’d be ready for opening night.

“Guys, do you think Stef got it?” he asked the room. Loud cheers replied and Ms. Sacks smiled. The band—Andy Crosby on guitar, his brother Matt Crosby on bass, keyboardist David Thompson and percussionist Howe Pearson—continued to lay down a funky rhythm.

Like everyone else who works at or with Camp Jabberwocky, the musicians are volunteers. And on Sunday, Matt Crosby is marrying another member of the camp family, longtime volunteer and director of development Kelsey Grousbeck, with all the campers and counselors invited.

Sister Act plays Friday and Saturday at 7 p.m. in the camp studio, a red barn-like building named Frabjous on the campus at 200 Greenwood avenue. Admission is free and all ages are welcome.