One Island institution is turning 25 this month, and Islanders are invited to its birthday bash.

Vashon Park District, which began with no property, no funding and only one part-time employee, has blossomed over the past two and a half decades into a thriving government agency responsible for more than 20 Island parks and dozens of improvement projects within them.

It’s holding a celebration on Thursday, June 18, to commemorate its quarter-century of existence. A cake beauty contest and live music will be featured as Islanders converge on Ober Park to wish the district a happy birthday.

“The park district today is so much more than we ever thought it would be,” said Bill Ameling, who has been a park board member since the district’s inception in 1984. “I think it’s one of the best success stories you’ll ever see — starting with nothing and growing to what it’s become.”

Ever since the park district’s acquisition of its first park, the north-end boat ramp, the organization has been a vehicle for preservation, restoration and improvement at its various recreation sites.

Because Vashon Park District is a governmental agency, it often accepts grant monies on behalf of Island groups that have a vision for one of the Island’s parks, and has been actively involved in the construction of buildings, the creation of a playground and the improvement of natural areas.

“The real power of the park district is that it exists,” Ameling said — it qualifies for a plethora of grants. “Just its existence gives people the chance to do what they wanted to do.”

The Jensen Point Boathouse, for instance — it was paid for by a massive fundraising push by Vashon’s rowing and kayaking community and a grant awarded to Vashon Park District. Or Paradise Ridge Park — it was one of the first parks acquired by the park district and was developed greatly by the Island’s equestrian community.

“That’s part of the success of the park district — it just empowered all those people to create what they did,” Ameling said.

Staff have planned an event next Thursday to celebrate the park as well as the community that supports it.

Susan McCabe, Vashon Park District’s program coordinator, said she hoped people would come to Ober Park on June 18 to celebrate the big day, and perhaps enter a cake in the cake beauty contest as well.

About 10 cakes are already in the works, she said.

Park programs including Vashon Lacrosse, Vashon Youth Baseball and Softball, Vashon Island Junior Civic Ballet, Vashon Island Junior Basketball and the Seals Swim Team have all pledged to create a cake for the contest, McCabe said.

The cakes will run the gamut from mermaids to ballet dancers.

Each cake could win one of a number of awards, including best depiction of a park, most beautiful and “best of show.” The winners, she said, will go home with “the honor of knowing they made the most beautiful cakes,” she said.

Winners will be chosen by a panel of judges as well as audience applause.

“The only requirement is that it be edible,” she said, adding that all Islanders are encouraged to enter the contest, not just those who are affiliated somehow with the park district or its programs.

Park staff will sell popcorn and 25th anniversary commemorative items, and a collection cup will be out, all to benefit the park district’s reduced fee fund, the coffers of which are quickly being drained by increased demand for program scholarships.

“What’s fun about the park district is it’s really all about fun,” said Wendy Braicks, the first employee the park district hired and today its executive director. “We’re always trying to think of things for people to do and places for them to do it.”

Next Thursday’s celebration is no exception. It’s the first in this year’s summer concert series, “Concerts in the Park,” where musicians bring their talents to Ober Park and the Village Green.

Pan Leggo, a Caribbean-style steel drum group, will regale partygoers at 7 p.m. Thursday, June 18. Vashon Allied Arts is cosponsoring the event celebrating the Island organization’s anniversary.

“We’ve sure done an awful lot in 25 years,” Braicks said. “I think it has snuck up on people that we’ve been here for 25 years — we’re such a part of this Island. I hope people come out and celebrate, and I hope people bake some good cakes.”