Maine State Music Theatre announced Friday it will require audience members to show proof of vaccination or a timely negative COVID-19 test to attend its shows in Westbrook starting next month, joining a growing list of arts and music presenters adopting similar requirements.

Because of pandemic-related delays, the theater, based on the Bowdoin College campus in Brunswick, planned its largest productions for the Westbrook Performing Arts Center, in order to avoid conflict with the college’s calendar. It presents the main-stage musicals “Jersey Boys” in Westbrook Sept. 1-19, and “Cinderella” Sept. 29-Oct. 17, along with “Alice in Wonderland” Sept. 9-10 and “The Rocky Horror Picture Show” Oct. 19-23.

“To ensure we are offering the safest environment possible for our patrons, actors, and staff, Maine State Music Theatre is requiring audience members to have proof of vaccination or a negative (within 48 hours) Covid-19 test to attend a performance for shows at the Westbrook Performing Arts Center,” according to the theater’s website. “Proof of vaccination can be a physical vaccine card or a photo of your card.”

In addition, all audience members must wear masks inside the theater. Children younger than 12, who are not eligible for vaccines yet, are exempt from the vaccination requirement. All actors and staff members are fully vaccinated, the theater noted, writing on its website, “We made this decision to keep the community safe.”

On Wednesday, the promoters of concerts at Thompson’s Point and the State Theatre said they would require proof of vaccination or a negative test to attend concerts beginning this weekend. The Portland House of Music will enact a similar measure beginning Thursday. Portland Ovations, which presents events across the city, also announced it would require vaccinations, as well as masks, at its indoor events, which begin next month, and would not permit children younger than 12 to attend.

“As soon as those under the age of 12 become eligible to receive a vaccine, fully vaccinated children will be welcomed back into our venues,” Portland Ovations said in a release.

At least two other Maine music venues already require proof of vaccination to attend concerts – The Opera House at Boothbay Harbor and Stone Mountain Arts Center in Brownfield – and several others are considering it.

Anita Stewart, executive and artistic director at Portland Stage, which is currently co-presenting the Johnny Cash musical “Ring of Fire” with Maine State, said theater staff members are discussing how to enact a proof-of-vaccination policy.

“We are talking extensively about the best plan. Because we have multiple performances, we are trying to see how we can best serve all our community,” she wrote in an email. “I know one of our big concerns is what the impact would be on people under 12 if we go the full vaccine route.”

The Ogunquit Playhouse does not require ticket holders to be vaccinated, and a spokesperson would not say Friday whether the theater is considering changing its policy.