As the Shakespeare Theatre Company’s “The Merchant of Venice” prepared to open at Sidney Harman Hall a few weeks ago, director Ethan McSweeny, watching in the darkened theater, plopped his 3-year-old nephew onto his lap. In the thick of technical rehearsals, McSweeny grabbed a phone to the lighting booth. He held it to his nephew’s ear and whispered, “Say, ‘Cue. Go.’ ”

The kid did it. “And all the lights moved,” McSweeny says a few days later. “He thought that was just the coolest thing.”

McSweeny, a Brooklyn-based director who grew up within view of the Kennedy Center, can let a tot twiddle the fixtures because for him, the Shakespeare Theatre Company is like family. Once upon a time, McSweeny was an enfant terrible with the company, interning before college, then returning as an associate director at 22. Now at 40 and as an affiliated artist with the troupe, his grandly scaled “Merchant of Venice,” with Jews and Italians jostling in a tough 1920s Lower East Side Manhattan, marks the first time he has directed Shakespeare for the theater where he came of age. The play runs through July 24.

This comes close after McSweeny’s staging of a vastly different courtroom drama, John Grisham’s “A Time to Kill.” As Arena Stage and New York producer Daryl Roth aimed an adaptation of Grisham’s 1989 novel toward Broadway, McSweeny was tapped to helm the project, his first gig at Arena.

It’s a delayed but gratifying local emergence for a director who has been making a name in top theaters around the country. Joe Dowling, the Irish-born artistic director of the Guthrie Theatre in Minneapolis, has known McSweeny “since he was a mere lad” at the Shakespeare. He “was blown away” by McSweeny’s production of the Leopold and Loeb drama “Never the Sinner,” a co-production between Signature Theatre and Rep Stage that went from here to New York in the 1990s. Since then, by Dowling’s reckoning, McSweeny has embarked on a “major career.”

Ethan McSweeny. (Amanda Voisard/THE WASHINGTON POST)

“I think he’s honestly the real thing,” says Michael Kahn, who just completed his 24th season as the Shakespeare’s artistic director. “He gets better and better every year. He’s sensitive to different kinds of material. He’s a really good director of actors. And he always has a visual sense of the play.”

Impressing masters from city to city can mean keeping a breakneck pace. “A Time to Kill” was a late addition to McSweeny’s slate this season, so in January he found himself squeezing in meetings with writer Rupert Holmes in New York’s Grand Central Terminal. That was just as his premiere production of Regina Taylor’s “Trinity River Plays” debuted at Chicago’s Goodman Theater, and as he was preparing George Bernard Shaw’s “Arms and the Man” for its March unveiling at the Guthrie.

The day after “Merchant” opened at the Harman in Washington, McSweeny held auditions for “Much Ado About Nothing,” slated for the Harman Hall in November. Then he decamped for western New York state, where he runs the summertime Chautauqua Theatre Company with his former flame, actress Vivienne Benesch. In the next six weeks he’ll direct a new-play workshop and “Love’s Labour’s Lost.”

“I never like to say the schedule’s full because I never want someone to not offer me a job,” McSweeny laughs.

“Thank God for Skype,” says Robert Chelimsky, Chautauqua’s managing director, about staying in touch with his boss.

In Washington, the McSweeny name is practically a brand. Ethan’s parents are vigorous patrons of the arts — his mother had a long tenure as chair of the D.C. Commission on the Arts and Humanities — and his sisters are high fliers in law (Kate, from father William’s first marriage, is with Chadbourne and Parke) and politics (Terrell advises Vice President Biden on domestic policy). Brother Bill is a judge in Massachusetts.

The parental courtship had a dateline of Vietnam, with Bill as a reporter and Dorothy working for USAID. “I think it was a lot like the movie ‘The Year of Living Dangerously,’ ” Ethan says. “Prominently featured on a shelf in the study are the keys from the Hotel Saigon, where they eloped. It’s tough to have that as part of your parents’ back story. I mean, what the heck am I going to do?”

He survived what he calls a “rough but large education” at St. Albans, then went through the school of hard knocks after leaving Kahn’s nest at the Shakespeare. Before he was 30, McSweeny was directing on Broadway — “The Best Man,” with a big-name but wrong-headed cast. A flop, to use Kahn’s word.

“He was treated like a young director by the producers,” Kahn says. “ ‘Fix this, change that.’ ”

But a period of seasoning was underway for the hotshot who is still unfailingly described as “smart,” with one to three “very”s modifying the noun. Longtime colleague and friend Karma Camp, a choreographer who worked with McSweeny when he was breaking in and lately on “Merchant,” notes that his intellect could lead him to be “quick with the sting.” McSweeny doesn’t dispute it.

“I had a kind of shoot-from-the-hip mentality,” he says. “The end result is all that matters, and let the bodies fall where they may.”

McSweeny wonders if a maturing process is what Kahn had in mind by not bringing him back to direct until 2006, with the Greek tragedy “The Persians.” Over coffee, Kahn grins in the affirmative. Acknowledging that neither of them is famous for suffering fools gladly, Kahn says: “He had a temper, but he’s really conquered that. That was a big deal.”

Now Kahn is full of praise for the visual and storytelling solutions McSweeny came up with for “Merchant,” set in a commerce-crazed Little Italy teeming with ethnic hostility. “The most complicated show he’s done,” Kahn suggests. (Reviewing the production in these pages, Peter Marks regarded that complexity as “forcibly contrived,” though he also called McSweeny “estimable.”)

Since his career is spread around the country, McSweeny can’t be sure how he’s viewed.

“Daryl Roth thought I lived in Washington,” he says with a near-despairing laugh. “I think that our overall artistic landscape vastly prefers you to specialize. And I’m a generalist. To really be a genuinely freelance director in this country is a little bit like being a jockey. You have to ride the horse that you’ve got.”

He’d like to try his hand at opera, and he’ll get a crack at Gilbert and Sullivan’s “Pirates of Penzance” in Stratford, Ontario, next spring. (He is being tutored to read music by girlfriend Nancy Anderson, who recently appeared in “Side by Side by Sondheim” at Signature.) In terms of style, McSweeny acknowledges a fondness for “moving your focus around the stage to show you different things, finding the theater versions of the close-up and the away shot and the crane shot.”

So is he ready for his close-up? Ready to add artistic director to his list of accomplishments?

“I think that’s always been a part of my career trajectory,” McSweeny says. He talks the head-honcho talk fluently — the value of company, the virtue of new work, the challenge of the shifting funding landscape, the imperative of fair prices for audiences.

“He deserves his opportunity to show his wares in his own house,” Dowling says. “And for American theater, Ethan is one of those who should be leading the way.”

Kahn says: “He’ll make a pretty significant artistic director. This is his time now.”

The Merchant of Venice

through July 24 at Sidney Harman Hall, 610 F St. NW, Washington. Information: shakespearetheatre.org.