The lights were low, the music was funky and party hats were everywhere as Camp Jabberwocky marked its 65th anniversary in Boston last Thursday night. About 150 people gathered to celebrate at the Lansdowne Pub near Fenway Park, many of them drawing their wheelchairs around low tables near the stage where a 10-piece band performed at conversation-friendly volume.

Three-year capital campaign will help renovate campus and create a tuition endowment. — Matt Cosby

This party was a reunion as well as a milestone. Months after the end of summer sessions on Martha’s Vineyard, virtually everyone in the room was smiling irrepressibly to be back in the company of friends — Jabberwocky campers, family members and staff alike.

And they are alike, said Sam Simcoe, a camp counselor since 2015. She calls her cabin charges “buddies” and “friends,” saying “We try not to use dividing language, because we’re all the same.”

Ms. Simcoe was so eager to see her summer friends again that several days before the party, she flew from her home in Tulsa, Okla., to Connecticut to meet up with two of them and drive them to Boston for the event. After the return trip to Connecticut, she then flew back to Tulsa with one of the two, Cy Brigish, for a visit with her family and friends before accompanying him back to his Connecticut home.

“He’s the best friend I could ever think of,” she said of Mr. Brigish, whose father Alan lives on the Vineyard. “He and I like all of the same things.”

Friendships forged at Camp Jabberwocky can last a lifetime. Many other camps for people with disabilities have age limits, but at Jabberwocky nobody ages out. Some campers arrive after hitting the age limit elsewhere, while others have been coming to Jabberwocky since childhood.

More than 150 counselors and campers gathered for the party. — Matt Cosby

Faith Carter of Whitman has been a summer camper since 1975. “I try to do something new every single year,” she said, in a speech from her wheelchair during Thursday’s party. Her 2017 goal was to ride a bike, Ms. Carter said, but her legs wouldn’t bend enough to turn the pedal crank all the way around.

Challenge accepted: A Jabberwocky staffer installed adaptive equipment that would permit Ms. Carter to crank the wheels, and she was off.

“I could go for a bike ride around camp without falling off, and then down the street, and it was amazing and it was a high that I rode for a really long time. And that was only one of the millions of miraculous things about camp,” Ms. Carter told the crowd, to cheers of “Forty-three more years!”

For Robert S. Devlin, of Arlington, 2017 was his 35th Jabberwocky summer and he’s already looking forward to next year. “All the people and all the fun,” particularly swimming at State Beach, he said.

Like all good Camp Jabberwocky outings, this one had both dancing and singing. The 10-piece Boston band SoulFood, whose drummer Hudson Bausman is a second-generation camp volunteer, had some audience members on their feet while others led the room in a rendition of the Lumineers’ winsome 2012 chart-topper Ho Hey.

The musicians donated their time for Thursday’s party after playing at Camp Jabberwocky last August before what their Facebook page admiringly called “easily the most hype crowd we’ve ever had.”

Celebration was held at the Landsdowne Pub near Fenway Park. — Matt Cosby

It costs about $1,450 a person to attend Camp Jabberwocky for a week, or $1,000 per family for the three-day Family Camps held in late summer. In keeping with the camp’s founding principle of accessibility set by the late Helen Lamb, who founded the camp, tuition is on a pay-what-you-can basis. No one is turned away for lack of funds.

“Everyone who works at camp is a volunteer,” said executive director Liza Gallagher. “It takes 150 volunteers and 200 campers every summer to make Jabberwocky happen. We have a huge wait list of people who want to volunteer.”

Kelsey Grousbeck started giving her time to the camp when she was 16, after her family chanced upon a Jabberwocky drumming session on the beach. Her younger brother is blind, and the Jabberwocky crew quickly pulled him and the rest of the Grousbecks into the fun, she said.

“The camp just absorbed us,” she said. “I wanted to be involved.”

A dozen Jabberwocky summers later, after earning an M.B.A. from Boston University, Ms. Grousbeck is the camp’s new director of outreach. At Thursday’s bash, she took the stage to share big news: After 65 years, Camp Jabberwocky is launching its first capital campaign.

The three-year campaign seeks to raise $3.5 million in two major phases, Ms. Grousbeck said. The first $1 million will go to renovate the 1960s-era main cabin on Greenwood avenue extension in Vineyard Haven, which serves as the dining hall and community gathering place. With a dropped ceiling, little natural light and fluorescent fixtures, the room is not only dated but hot and cramped.

Camp began in 1953, founded by Helen Lamb, a British speech pathologist. — Matt Cosby

“It feels like you’re in a very sweaty, loud doctor’s waiting room,” she said. The renovation will raise the ceiling, remove all asbestos, add windows for sunlight and winterize the facility so it can be used by the Island community off-season.

“It’s actually going to be a community center,” with an updated kitchen and screened porch, Ms. Grousbeck said.

The second phase of the campaign will build a tuition endowment. Sending a letter each year asking families to pay what they can is not in keeping with the Jabberwocky way, Ms. Grousbeck said.

“We’re not people providing a service for campers, we are a group of friends hanging out and sharing activities together,” she said, to cheers.

“We don’t charge camp counselors to come, why should we charge campers? And since we’re not going to start charging counselors,” (“Thank you!” cried a voice from the room) “instead we’re just going to get rid of tuition altogether,” Ms. Grousbeck said.

The $2.5 million in this phase will cover the current tuition shortfall and provide what Ms. Grousbeck called “the beginning of hopefully a very beautiful and gigantic endowment that will make sure that Jabberwocky gets to spread its joy for the next 65 years and 65 beyond that and always.”

Even before Thursday’s announcement, the capital campaign was off to a good start: Donors have already contributed $1.4 million, Ms. Grousbeck said.

With an updated main cabin and tuition support, Ms. Gallagher said, Jabberwocky will be able to serve more campers for more months of the year.

“We are busting at the seams with every bed at camp filled,” she said. “We see the need for Jabberwocky for so many more families.”