Tony-winning Signature Theatre has always gone its own way, musically speaking — especially when it comes to scouring the countryside for original material. This season alone, the Shirlington-based company will be producing three world-premiere musicals, a world-premiere revue and a new version of another musical, “Elmer Gantry,” that never made it to Broadway. And now, in furtherance of these efforts, the company is adding a new member to its leadership, a seasoned director-playwright with deep roots in musical and play development. Joe Calarco, whose work as a freelance director for Signature has included well-received revivals of “Gypsy,” “Assassins” and “Urinetown,” as well as stagings of his own plays, will be joining Signature on Dec. 1 in the position of resident director and director of new works.

While dramaturges at some companies are involved in finding and honing new plays, the establishment of a full-time job with a primary emphasis on the creation of new musicals, as well as plays, is surprisingly rare in the theater. That it is being filled by a director — and one of Calarco’s caliber — stamps the move as especially significant. Calarco, who has directed 14 productions at Signature, starting with playwright Norman Allen’s “Nijinsky’s Last Dance” in 1998, joins a producing team led by longtime Artistic Director Eric Schaeffer, Associate Artistic Director Matthew Gardiner and Managing Director Maggie Boland.

“It couldn’t be the more perfect position. I love the city,” Calarco said of the job and of Washington, as he was preparing to direct a new musical, “The Circus in Winter,” in Connecticut. “And,” he added, “it’s the perfect theater in that city.”

Schaeffer says Calarco was recruited because of a realization that the task of finding, nurturing and producing new musicals was more than he and Gardiner, who direct the bulk of the company’s main stage shows, could reasonably handle. (Schaeffer also takes on high-profile projects away from Signature, such as a forthcoming pre-Broadway tryout of “Gigi” at the Kennedy Center.) Signature’s American Musical Voices Project — whose new-musical production history began with the 2009 premiere of “Giant” — needed its own guiding force, Schaeffer said. And he recognized in Calarco, until now a New York-based director whose work has taken him to many regional theaters, a person with connections that might make it easier for musicals developed at Signature to be produced again elsewhere.

“The hardest thing is not getting the first production done, it’s getting the second production done,” Schaeffer explained the other day, before starting a rehearsal for “Elmer Gantry,” which begins performances next month. “I also think he understands who we are. He gets what Signature is, and he knows the kind of work that could work at Signature.”

Joe Calarco will join the Signature Theatre on Dec. 1 as resident director and director of new works. (Christopher Mueller/Signature Theatre)

With 40 full-time employees and a $7.5 million operating budget, 25-year-old Signature is a mid-sized theater company that has to think hard about adding staff. Schaeffer said that while the company hadn’t allocated funds ahead of time for the position, he approached the Signature board with a plan to trim other expenses and hire Calarco, and “they said, ‘Let’s go for it.’ ” (As is common in such situations, the salary was not publicly disclosed.)

The company’s heavy volume of untested work means the troupe often faces tougher marketing challenges, as well as a higher risk of a production falling short artistically; Calarco’s hiring adds to the brain trust determining when a musical is ready for Signature’s main stage.

Calarco and Schaeffer say his portfolio at Signature will include his continuing involvement in the Signature in the Schools program, for which he’s been writing shows for several years. Plans also call for him to direct one or two major productions a year, and to curate a new festival each summer of musicals-in-progress.

Calarco says he’s hoping to create short residencies for composers, lyricists and book writers in Shirlington, much the way he was once invited by the National Theatre in London to work on a project there, free of any producing pressure. He says he’s excited about moving to Washington, where his sister Renee, a playwright, already lives (and has her own new play on Theater J’s roster this season). In the meantime, he has a new adaptation of “The Nutcracker” to direct this fall, at Round House Theatre, and then, for the first time since high school, an actual full-time job. “I’m sure once the news gets out,” he said, “I’ll be getting a lot of calls — and scripts.”

An earlier version of this article misstated the number of Signature productions Calarco has directed.