When John Erickson came to Acadia Repertory Theatre to perform the lead role of Bob in Jean Kerr’s play “Mary, Mary,” he had no idea that two decades later, he would be one of the long-standing company members. This summer, Erickson will reprise the role at the Somesville theater, founded in 1973 by George Vafiadis.

“Twenty years ago, when it first started, Acadia was a bold new venture,” says Erickson, now Acadia Rep’s producing director, and a teacher at Bangor High School. “I had no idea what I was getting myself into. It just took off like crazy.”

After that first season, Vafiadis extended the company to a Bangor location, which later became the Penobscot Theatre. For 10 years, the two venues were jointly run. Today they are no longer affiliated. But Acadia Rep has thrived as a boon for locals, a nearby treat for Bangorites, and an additional island treasure for vacationers.

Everything from Greek comedy to Neil Simon has echoed through the open-space room at the 135-seat Masonic Hall, where the company has been performing for all 20 seasons. Whereas serious drama was once the backbone of the theater, comedies such as Noel Coward’s “Private Lives,” and mysteries such as Agatha Christie’s “Mousetrap,” have been the most popular fare in the past three years.

Artistic director Kenneth Stack describes recent seasons as the “best ever.”

“We feel responsible to provide what our patrons want, and many of them are well grounded in solid literature,” says Stack, who will perform this summer in “Stage Struck” by Simon Gray. “We are not highly experimental, but we’re not fluff either. The work is solid entertainment that is also thought-provoking.”

Stack joined the company a year after Erickson, and, except for a few tours and jobs elsewhere, has been working devoutly at Acadia Rep. As with Erickson, Stack was drawn to the beauty of the island, and to Vafiadis’ vision of finding a theater company that would stay together over several seasons and develop as an efficient and gifted ensemble.

As soon as he set foot on island soil, Stack knew there was something special about Acadia Rep.

“I was taken by the incredible support the community had for this little theater in a small community, in a small town in Maine,” says Stack. “You felt like you were performing for friends. And I have found it constantly rewarding and ever renewing to work in this theater and work in this area. It’s nice to work for friends rather than faceless people in the dark. Even people who are visiting from Florida are caught up in the atmosphere of a friendly, summer-stock theater in Maine.”

Somesville residents Mary and Joseph Gilliland, who have lived next door to the theater for all 20 seasons, have been drawn in by both the friendliness and the talent of their thespian neighbors. The Gillilands have always attended performances and have hosted Acadia Rep actors as roomers.

“We feel like they’ve been very good neighbors. For the most part, we think the work has been good, and some years, it has been excellent,” says Mrs. Gilliland.

That excellence has also attracted the patronage of well-known local figures, such as the Rockefellers, Mrs. Vincent Astor, and Caspar Weinberger.

Several theaters that have tried to establish residences on Mount Desert Island have not had the same good reputation or success as Acadia Rep, which has both survived and grown. In the first season, the company offered only four shows, which ran from July 4 until Labor Day. This year, the season begins April 30 with a dinner theater performance at the Lucerne Inn, and opens officially in Somesville on June 19. Five shows, plus weekly children’s theater (performed by members of the Acadia Rep intern-apprentice program), and a regular guest spot for entertainer Jackson Gillman, will run through Aug. 30. During September, four of the shows will be revived for a week each.

“What we’ve tried to do this season is pick a series of plays that has been very successful, and is exemplary of what we try to do at Acadia,” says Erickson. “We’ve got some good family entertainment. We’ve taken some risks with some plays and picked some others because we know they are crowd-pleasers.”