The quiet little seaside town of Marion has been a longtime summer draw for owners of second homes and sailors from around the globe.

And for the past two decades, it’s also been a haven of free world-class music: This year marks the 20th anniversary of the Buzzards Bay Musicfest, running from Wednesday, July 13, through Sunday, July 17, at the Fireman Performing Arts Center at Tabor Academy, where prominent musicians perform orchestral, chamber, and jazz music. There is no cost to get in, but donations are accepted.

“It’s been a great event right from the start,’’ said Trudy Kingery, chairwoman of the event and one of its founders. “The first year we had 25 musicians, and this year we have 40, all of whom stay for the week with families in town. Some have stayed with the same family for 20 years.’’

The house was packed the first year, she said, and it has been ever since at the 650-seat Fireman Center.

“We draw mainly from our local area, but would love to see more people come down from Boston,’’ Kingery said. “The music is truly outstanding.’’

This year’s music features works by Mozart, Hummel, Shostakovich, Tchaikovsky, Haydn, and Beethoven, among others, under the artistic directorship of Charles Stegeman. Antony Walker, the current music director of the Pittsburgh Opera and formerly of the Sydney Philharmonia Chorus, returns as guest maestro.

Musicians come from as far away as Brazil and Europe, Kingery said. The sole local musician performing is Marion resident and professional flutist Wendy Rolfe, who performs, records, and tours with the Handel and Haydn Society, Boston Baroque, Toronto’s Tafelmusik Baroque Orchestra, and other musical entities.

Two years ago, jazz was introduced and proved a popular addition. The Sean Jones Quartet performed, a group that included Orrin Evans, a Pew Fellow and two-time Grammy nominee. Evans returns this year with his own quartet, which includes saxophonist Stacy Dillard, bassist Luques Curtis, and drummer Mark Whitfield.

About 10 years ago, Kingery said, an open rehearsal for children was added, allowing aspiring musicians to watch and listen to artists rehearse and get a chance to chat with them after.

“That’s really nice, the children enjoy watching them play and talking with them,’’ she said.

The festival does little advertising, Kingery said, but still draws capacity crowds.

“Marion has a lot going on, but not a lot of music in the summer,’’ she said. “These musicians are world-class, and word spread pretty quickly.’’

Putting together the annual show is a huge undertaking, Kingery said, mostly to gather the $100,000 or so needed to put it on. The festival receives a small amount from the Buzzards Bay Musicfest Foundation, she said, but 97 percent of funding comes from donations.

“I send out letters every year, and people give because it’s such a great event,’’ Kingery said, adding with a laugh, “but sometimes people cross the street when they see me coming.’’

For events, check www.buzzardsbaymusicfest.com

Paul E. Kandarian can be reached at pkandarian@ aol.com.