“A lot of people who think they don’t like opera have just never heard an opera singer live,” Timothy O’Leary says.

O’Leary, 42, has already convinced a lot of people about opera. In a 10-year tenure as general director of the Opera Theater of St. Louis, he expanded the budget and endowment by millions of dollars, while mounting interesting productions that got people talking — even winning audiences over to operas that other audiences haven’t liked. At the Metropolitan Opera, John Adams’s “The Death of Klinghoffer,” a piece about Palestinian terrorists hijacking the cruise ship Achille Lauro, drew vocal protests. In St. Louis, thanks to the opera company’s active involvement, it created interfaith discussion groups that are still active seven years later.

And as of July 1, O’Leary has been bringing his experience, and his potential, and his pragmatism to the position of general director at the Washington National Opera.

The companies in St. Louis and Washington are very different animals. St. Louis is a festival, where an intense five- or six-week season, attended by audiences from around the world, is followed by a whole year of planning and gestation. Washington, by contrast, has a year-round season but plays more to local audiences. It seldom offers fare that people would travel to, with some notable exceptions such as the recent “Ring.” When the season is longer, carving out time to be creative, to come up with new ideas and initiatives, is a challenge. “That time I’m used to having to create the underpinning that creates all that excitement,” O’Leary says, “is time I’m going to have to find differently.”

But there’s no reason some lessons learned in St. Louis might not transfer to Washington. One of St. Louis’s initiatives, thanks to a Wallace Foundation grant, was a program designed to attract new audiences through evenings that paired food with live performance at restaurants and bars around the city. “There’s something about being in an intimate space and hearing that sound,” O’Leary says. “People would have these conversion moments.” He remembers one woman’s reaction to the tenor Joshua Blue. “I have seen this happen in movies,” she said, “but you opened your mouth to sing, and I began to cry.” Will WNO begin trying similar outreach? Coincidentally, Blue happens to be about to start in his first season in WNO’S Domingo-Cafritz young artist program.

That’s not O’Leary’s doing. Opera plans its schedules so far in advance, it will take a season or two to discern his direct influence. The opera world is watching to see how he will work with Francesca Zambello, WNO’s talented and turbulent artistic director, who has worked hard to present herself as the company’s public face. O’Leary raves about Zambello as one of his major influences, ever since he saw her production of Gluck’s “Iphigenie en Tauride” — not always a gripping evening of theater — when he was in his first season working for the New York City Opera. But O’Leary’s presence is also a clear sign that Zambello no longer rules the WNO roost alone.

O’Leary is realistic about the art form he loves. Idealist though he is, he acknowledges that among people who don’t know about the form, “the stereotypes associated with opera are unbelievably negative.”

“I wish I personally could talk to every person in the marketplace,” he says. “Because one of the things I have learned as a person who loves opera is that if you are able to acknowledge to a person who’s feeling skeptical that it is a ridiculous way to tell a story, that there is a kind of absurdity to it, and we know that . . . when you are real with people, you sort of win their trust.” Opera, he feels, “has all the appeal it always had. We [just] have to give people the way in.”