“In the theater, it’s all about timing, isn’t it?” Kate Maguire is commenting on the concatenation of circumstances that doubled her job description last month. Until then, she was wearing two hats: artistic director and CEO of the Berkshire Theatre Festival in Stockbridge. Now she’s sporting four, having just taken on those two jobs at Pittsfield’s Colonial Theatre as well.

It all began last summer, Maguire says. “I’d been thinking, surely, considering the times we’re living in, there should be ways for all of us in the Berkshires’ cultural community to find ways we can collaborate to operate more efficiently.”

At the same time, she was doing some forward thinking about the BTF’s seasonal production of A Christmas Carol, whose fifth annual staging opened last weekend: “We were recognizing that it was really needing some expansion.” The show performs in BTF’s Unicorn Theatre, a 120-seat matchbox with a stage that barely contains the overflowing cast. The company’s mainstage, a Victorian bijou that seats 400, has been a summer theater and only a summer theater since 1928, and has no heating.

Maguire approached the Colonial’s staff to feel out the idea of performing A Christmas Carol there in the future, and found the organization at a turning point. Its executive director having recently departed, “They were seeking ways to figure out their executive structure. They said, ‘Why don’t we really talk about a partnership and collaboration?’ So I literally walked in the door at exactly the right time.”

Things moved very quickly, she says. “It all laid out in such a way that there were far more synergies than not,” and on November 19th, the two organizations announced a formal partnership, with the intention of working toward a merger.

Although the two theaters maintain separate financial systems and somewhat separate staffs, as well as their distinct identities, Maguire is already seeing them as a two-town unit. “Artistically, I think of it as having three stages,” she says. The partnership gives new scope and flexibility to both theaters’ programming possibilities. BTF gains a larger venue in the 800-seat Colonial—itself an architectural gem dating from 1903, which has been lovingly restored to its Gilded Age splendor—and the Colonial’s programmer has the opportunity to book more intimate shows in the Unicorn.

The performance lineup at the Colonial, which has operated primarily as a concert hall since reopening in 2006, is already set through next May, so Maguire is now thinking about “what happens in June and the rest of next year”—which happens to coincide with the start of BTF’s 2011 summer season.

Although aimed at cost-cutting by combining resources, the new union hasn’t resulted in a wholesale slashing of staff positions, largely because the Colonial had already shed some jobs. The two companies now share a financial officer and a development director, as well as Kate Maguire, who now has not only four hats but two offices, one in Stockbridge and one in Pittsfield.

A Christmas Carol: through Dec. 30, $15-20, plays at Berkshire Theatre Festival, East St., Stockbridge, (413) 298-5576, www.berkshiretheatre.org.