WASHINGTON, D.C. — It seems appropriate that Signature Theater will premiere an ambitious American musical and launch a multiproject creative development program just days after the Arlington, Va.-based org was announced as the recipient of this year’s Tony Award for regional theater.

As nonprofits tighten their programming belts, Signature heads in the opposite direction with the May 10 bow of “Giant.” The new tuner from composer Michael John LaChiusa and playwright Sybille Pearson is based on the sprawling Edna Ferber novel about the Texas oil boom that was also the basis of the 1956 film. The Texas-sized production, staged by Jonathan Butterell, sports three acts, 21 players, a 15-member orchestra and a running time approaching four hours.

Is “Giant” another economically contrarian selection by the troupe that just mounted “Les Miserables”?

Not entirely. LaChiusa is the first of three beneficiaries of Signature’s American Musical Voices Project, a program aimed at assisting emerging composers in the creation of new musical theater works. Supported by a $1 million grant from philanthropists Ted and Mary Jo Shen, it hands recipients free rein to develop a work of their choosing.

The other two selected composers are Ricky Ian Gordon (“The Grapes of Wrath” opera) and Joseph Thalken (“Harold and Maude: The Musical”). Gordon’s project, “Sycamore Trees,” is slated for next season, followed in 2011-12 by Thalken’s still-untitled tuner.

Artistic freedom is only one of the program’s unique elements, says Signature a.d. Eric Schaeffer. Each composer is guaranteed a full production on Signature’s main stage, $25,000 a year for four years, and health insurance for five years. “These provisions enable them to concentrate entirely on their work,” says Schaeffer, who is producing as well as providing artistic advice, concept development and readings. He says “Giant” scripter Pearson is also receiving a commission.

A second phase of the Voices project dubbed “The Next Generation” assists three additional young composers in developing full-length musicals. Matt Conner, Adam Gwon and Gabriel Kahane have each received $25,000 in a one-year program that culminates this summer with a three-week rehearsal program and two cabaret perfs. Signature has also awarded stipends to composers Peter Foley and Marisa Michelson to support the writing of new songs for an upcoming concert at the theater.

Signature’s production of “Giant” is receiving an additional $50,000 in support from the Kennedy Center’s Fund for New American Plays. Cast includes Lewis Cleale “) as Jordan “Bick” Benedict, Betsy Morgan as wife Leslie and Ashley Robinson as Jett, roles played in the George Stevens film by Rock Hudson, Elizabeth Taylor and James Dean, respectively..

LaChiusa, known for favoring risky projects, had actually been approached earlier by a descendant of author Ferber to turn the mammoth story into a musical. When Schaeffer called with the unconditional Shen Family grant, he jumped at the chance. Schaeffer refers to “Giant” as LaChiusa’s “Angels in America: The Musical,” with its deep and emotional songs that capture the sweeping epic’s varied moods and predicaments.

The Shen Family Foundation has previously supported LaChiusa in eight separate projects, including Signature’s 2004 production of “The Highest Yellow” and the Public Theater’s 2005 mounting of the brooding “See What I Wanna See.” (The latter is playing at Signature’s smaller Ark Theater as part of a mini-LaChiusa festival.) Gordon and Thalken have also received past support from the Shens.

The foundation is digging even deeper to accommodate the demands of the mammoth “Giant.” It funded a requested 56-hour reading of the musical, which also required permission from Actors’ Equity, along with seven full weeks of rehearsal — all for a production that, given its girth, would appear to have limited potential beyond the Signature run.

“Our goal is to produce the best show for Signature and let the future take care of itself,” Schaeffer says.

The creative team includes Dane Laffrey (set), Susan Hilferty (costumes), Japhy Weideman (lighting), Chris Fenwick (music direction) and Bruce Coughlin (orchestrations).

As for the Tony honor, Schaeffer says: “It’s great for Signature and recognizes the work that we do. But I also think it’s great for theater in Washington. It just recognizes what an important theater town this is.”