On a Tuesday evening not long ago, half a dozen parents hurried into the Arden Theatre Company's new building for Philly's latest premiere: a theatrical adaptation of the video game Minecraft.The play, created and performed by ebullient third and fourth graders, wasn't quite ready for the main stage. But the fact that it was performed at all was a remarkable accomplishment given the venue: the Arden's brand-new, $5.8 million Hamilton Family Arts Center.

After all, the company bought the 22,000-square-foot industrial building, just up Second Street from its theater, in the depths of the recession. By last month's ribbon-cutting, the capital campaign was 98 percent funded.

That's a rare feat in a financially strained and arguably overbuilt local theater landscape. In recent years, some companies that planned large expansions have had to weigh the risks. The Philadelphia Theatre Company went ahead with its plan but moved into the Suzanne Roberts Theatre in 2007 $10 million short on its capital campaign. Meanwhile, the Walnut Street Theatre, which unfurled a vision for a 300-seat theater-in-the-round in 2008, has not moved on the project since.

So how did the Arden do what it did? Artistic director Terrence Nolen said the keys were taking an incremental approach to growth, and coming up with creative ways to engage supporters.

That pragmatism appealed to Susan Sherman, chief executive of the Independence Foundation, which supported the project with a $100,000 challenge grant.

"There's a sense on the parts of some organizations that if we build it they will come, and that will take care of the debts. And when they get built, that doesn't happen - so people are caught up short," she said. "I don't see the Arden in that sense. I see the Arden as building it because they've already come. They're accommodating audiences they already have rather than trying to find audiences to fill a new space."

The Arden has operated that way since it moved to an industrial space in Old City in 1995. (Then-Mayor Ed Rendell at the opening of the half-finished space called it "a dump" under his breath, Nolen recalled.) They developed only the 175-seat theater in the front of the building before eventually raising funds to build out the 400-seat main stage and refurbish other spaces.

By 2010, the need to grow again was evident. The building could no longer contain the 1,200 students at camps and after-school classes. "We would have classes in the lobby, in the vestibule of the theater, sometimes in the conference room," Nolen said. "We were bursting at the seams."

So when they found the $1.5 million building up the street, they couldn't pass it up. But they couldn't afford to start renovating it, either.

They made a down payment and started rounding up already-staunch supporters, like Rendell, who helped them get $1 million in state funding, and Peter Hamilton, whose family donated another $1 million.

That meant there was still $3.8 million to raise, in a shaky economy. Fortunately, Nolen said, there was no rush. "We didn't want to get overextended. We said, 'If the building sits for many years, that's OK.' We didn't have an unforgiving timeline."

That left time to plan how to use the space. It now comprises six classrooms; one of the only dedicated rehearsal spaces in town to boast windows; large set-building and painting studios; and an 80-seat studio theater.

It also bought them time to figure out how to communicate that vision.

Word of mouth has always been the primary way the Arden has attracted new audiences and members. So they decided to stay true to what had worked. "We felt that if we kept telling the story, we'd be able to raise the money," Nolen said.

The problem was getting the right people to tell it - and enough of them to make a difference.

They created a program called Arden Ambassadors - 35 supporters, acting teachers, performers, playwrights, and former students. As work progressed, they leaned on the ambassadors to lead tours of the center, address fund-raising events, and spread the word.

Actors explained why the airy new rehearsal space beat the old one. Scenic designers told tour groups how much more efficiently they could work in a shop large enough to hold sets built in one stage-ready piece. Teachers spoke of students' need for consistency in the form of actual classrooms.

Playwright Michael Hollinger, who has had plays premiered at the Arden, participated in the program. He has noticed that when supporters can connect directly with the artists, "That's satisfying and rewarding. That feels like it's not 'I wrote a check to people in an office somewhere.' It feels like 'I'm feeding the art.' "

Hollinger, often asked to spend time with donors when his plays are staged, said being an ambassador was different. "To some degree you're actually a representative of the theater. I contribute to a variety of arts nonprofits," he said, "but I don't necessarily consider myself their advocate in the world. I did with the Arden project."

Hether Smith, a board member who cochaired the program, said outreach is an ongoing effort.

The key, she said, is that the Arden feels like a "giant family" but it's run like a business: Donors may have been charmed by artists like Hollinger, but some undoubtedly were sold by the fact that the Arden has been in the black nearly every year.

"I bet you every arts organization in the city has a copy of the Arden's strategic plan," Smith added. "I've used it on three different organizations that I'm on the board of."

By the time the Arden commenced work, the project was 90 percent funded. (A $4 million bridge loan enabled them to pay contractors; by the end of the campaign, managing director Amy Murphy expects to pay off that loan and be left with a $1 million mortgage.) Along the way, the company also raised an extra $850,000 for operating expenses and programming, including a new teen education program.

The center, however, is not finished. Nolen envisions a basement technology and recording studio; the studio theater won't be ready until next fall.

The incremental approach, in other words, is still in effect.

"It will probably be many years before this building is everything we want it to be," Nolen said. "Actually," he added with a grin, "there's air rights for another three floors."

So, with patience and the right team of ambassadors, the sky's the limit.