The towpath down in Georgetown is crowded with lights and cameras and boom mikes and film crew members, and by now small groups of spectators have gathered, sensing something is happening. It's a warm May day and in the middle of all this, somewhere, is a former D.C. kid, a guy who vaulted from Lafayette Elementary all the way to the Hollywood director's chair. He's the cause of this, David Dobkin is, because when he got the chance to film part of his third feature on location, the location he wanted was home.

So now Vince Vaughn and Owen Wilson are in town, popping up at Republican hotel parties and Adams Morgan bars, and traffic-clogged Georgetown is a little more clogged and, at the moment, passersby are craning their necks, trying to figure out where the famous people are. And, yep, there's Wilson, who is looking very Jeff Spicoli at first glance, though in this film he is apparently not channeling Sean Penn's slacker from Ridgemont High, but rather plays a lovesick thirty-something guy who has finally decided to grow up. ("I better say romantic comedy," Wilson answers, when asked about the film later, "because I've done so many buddy movies.") Meanwhile, his buddy Vaughn is down in his trailer at 3300 K St. NW, explaining, in detail, that it's not at all true that he never gets the girl at the end of his flicks.

"But enough about me," he concludes, adding a theatrical sigh. "This is about David."

Ah, yes, David. Dobkin. Here he is, dressed in a baseball cap and jeans, looking like a kid despite the fact that he's 34 years old now and in charge. He's pausing between shots, getting ready to powwow with Wilson, and as he looks around at the usual film-set chaos he forgets, for a minute, where he is.

"When I first scouted, I was like, 'Wow! It's home! It's my home town!' " Dobkin says. "Then you start shooting and it turns into a set. A location."

Dobkin and his team arrived early this month for a whirlwind four-day shoot before heading out to Easton, Md. Locations for the movie, "The Wedding Crashers" (set for release next year), included the Georgetown canal, at a church near DuPont Circle, and the Lincoln Memorial, where Dobkin dragged Vaughn and Wilson for a sunrise shot on their first day of filming. He's always had what he calls a "weird emotional attachment" to the Mall and its memorials and monuments, so he was determined to shoot there.

"I'm a big fan of Woody Allen," Dobkin says, talking about Allen's famous montage of his home city at the opening to "Manhattan." "I wanted to do that. I wanted to do my love letter to Washington."

Dobkin's childhood is a road map of traditional Washington institutions: long conversations on the Mall with his friends, Saturday afternoons at the Hirshhorn with his dad, an attorney, birthdays celebrated at the Palm. He became a Bethesda suburbanite as a child, and was known to haunt Georgetown. His favorite sandwich is the "Patty Hearst," from Booeymonger's: turkey, provolone, bacon, Russian dressing. Dobkin still makes them put it on an English muffin, as they did in the old days (nowadays it comes on French).

"Sometimes I order it when I land at the airport and have it waiting before I go to the hotel," he says.

It's evening now and he's back at the hotel, the Four Seasons in Georgetown, and he's hungry after a long day of filming. The producers -- Andrew Panay and Peter Abrams -- have a table at Cafe Milano for dinner, but as usual Dobkin won't be joining them. He's a workaholic. He'll swear he's coming, then he'll start looking at film in his room, and he'll go over a scene with Vaughn, and before he knows it he'll be dialing room service and settling in to work past midnight.

"David's very astute," Vaughn says. "He takes his job very seriously. He works harder than -- or as hard, I should say -- than any director I've ever worked with. It means the world to him. He's really like a child playing make-believe with toys or drawing something with crayons who takes it extremely seriously. You're really impressed -- like, 'Wow, your imagination is this strong.' "

Dobkin grew up in northwest D.C. and then Bethesda, where he graduated from Walt Whitman High. His dad -- who is now deceased -- was an attorney at Arnold & Porter by day and an abstract expressionist painter by night. Dobkin remembers him coming home from work, changing clothes and heading to his studio, where he would "stretch a canvas across the floor, put on Pink Floyd's 'The Wall,' attach some paintbrushes to the ends of broomsticks and start dancing around." He referred to the Palm as the "cafeteria" since his offices were directly above, and David became a regular at a very young age.

Dobkin fell in love with movies in the era of "Star Wars" and "Close Encounters of the Third Kind," and fell in love with moviemaking after a one-week stint as a production assistant on the set of "The Believers" when he was 14. Monty Diamond, the film's director, happened to be the son of one of the partners at Arnold & Porter, and gave the kid the gig. He also gave Dobkin some valuable advice upon his graduation from NYU: If you want to make it as a director, direct -- and only direct -- even if it means you starve.

So Dobkin directed. He made karaoke videos ("Lots of shots of couples running down the beach," he says). He begged and pleaded and wheedled his way into Virgin Records and Interscope, where he did some music videos on spec and wound up directing two Tupac Shakur videos at the age of 23. Then he branched out into commercials -- again starting with work done on spec -- and eventually landed at Ridley and Tony Scott's production company. The Scotts financed "Clay Pigeons," Dobkin's first film, which he made at age 27.

"I was dying to make a movie," Dobkin says. "It was all really exciting. And I'm so lucky because the great thing about commercials and music videos is you learn to communicate."

But "Clay Pigeons" typecast Dobkin -- who describes himself, accurately, as "bouncy and nice" -- as someone "very weird, dark and creepy" in the minds of Hollywood producers, and he kept getting passed over for future projects. So, more commercials it was until the opportunity to do "Shanghai Knights" arose 41/2 years later.

Meanwhile, though, he and Vaughn had hit it off on "Pigeons," forming a fast and lasting friendship, and Dobkin was itching to do another project with him. After getting to know Wilson -- who was in "Shanghai Knights" -- Dobkin liked the idea of putting the two together. And when his agent passed along the screenplay to "Wedding Crashers," he knew he had his film.

The movie is the story of two divorce lawyers, Jeremy (Vaughn) and John (Wilson), who make a habit of crashing weddings to meet women. Only after crashing one particularly high-powered wedding, John finds himself falling for a girl (Rachel McAdams as the daughter of the treasury secretary, played by Christopher Walken). His relationship with Jeremy suffers as a result, as the two struggle with the idea of finally becoming "grown-ups" at age thirty-something.

"It is about two friends who have kind of crutched on each other for a long time and avoided relationships," says Dobkin, who has a girlfriend. "It's a coming-of-age story for 35-year-old men, which is pathetic. But we've reached that point, haven't we? . . . And of course these two" -- Vaughn and Wilson -- "are still having their coming-of-age stories, so it's perfect for them."

Wilson disputes that. A little. The characters, he says, do have "shades of Vince," but he is another story. Beneath that slacker exterior -- "I'm big into R&R," Wilson drawls -- is a softhearted guy.

"I have a girlfriend I like a lot," he says.

What's clear, though, is that Vaughn, Wilson and Dobkin make quite a thirty-something triumvirate -- or "trifecta," as Vaughn likes to say. And, for once, putting the whole package together wasn't all that hard (at least by Hollywood standards).

Dobkin started by calling Wilson, who was filming in Mexico, to see if he liked the script and a pairing with Vaughn. Wilson was interested. So then Dobkin went over to Vaughn's house to watch "Monday Night Football" and laid the plan out for him. Vaughn was in. New Line agreed to finance the project, and producers Panay and Abrams were happy to have Dobkin, whose work they admired in "Shanghai Knights."

It was perfect -- almost. Originally the script called for the movie to be set in Boston. But in a nice little twist -- at least, in Dobkin's eyes -- it was going to be too cold in Boston and on Martha's Vineyard (part of the film is set at a Kennedyesque beach compound, hence the current filming on the Eastern Shore) when Vaughn and Wilson were available for filming. So since Walken's character had a political background, Dobkin used it as an excuse to push for the relocation to Washington. His mother had just moved to New York, alas, so Dobkin no longer had a house to come to here, but he still considers it home.

"I love this city," says Dobkin, who has lived in Los Angeles for more than a decade now. "I love coming back to it."

Luckily, the producers were sold on the idea of Washington as well.

"He wants the best, and that's what I love about him," Panay says now, after watching Dobkin at work in Washington. "I've never felt led that way before. Everyone is using the term 'He works so hard, he works so hard,' but he doesn't talk about it. You see it. He's always the first one on the set."

Like the first day of filming here, when call time for the actors was -- groan -- 4 a.m. But you have to be early if you want to film on the Mall, so there they were, at first light, filming against the backdrop of good old Abe.

"I had so many great experiences on the Mall -- whether it was going down on the Fourth of July when the Beach Boys played there, or just hanging out with friends late at night," says Dobkin, who made his first film at NYU about the Vietnam Veterans Memorial. "I had so many deep conversations and big moments in my life there. . . . That area has always had a huge impact, so I was really dying to have the opportunity to film there."

So when it finally happened, he had fun with it. Vaughn got into one of his improvisational modes, riffing with Wilson about the men of "thirtysomething," and how if Elliott didn't have to grow up, neither did he. Wilson pulled out a cell phone and called his mom and dad to tell them where he was shooting. Dobkin invited his best friend from first grade, Jeremy Lippman, to come on location and be an extra. Later in the day, filming at another spot on Capitol Hill, Dobkin included cameos by two of his favorite Washington people -- Sen. John McCain and James Carville. (Once asked what three people, living or dead, he'd like to dine with, Dobkin said Bill Clinton, Albert Einstein and . . . Carville).

If he was going to be the kid in the candy store -- and that, Dobkin says, is what it felt like -- he was going to take every advantage.

"It was so cool," Dobkin says. "That was one of the best days of my filmmaking career."

"I love this city," says David Dobkin, here setting up a shot in Georgetown earlier this month. "I love coming back to it.""Wedding Crashers" producer Andrew Panay, left, and star Vince Vaughn with Kay Kendall and Rep. Harold Ford at a Washington Ballet gala last week.Owen Wilson (with Ben Stiller in February) stars in "The Wedding Crashers."David Dobkin, at left and above (with "Wedding Crashers" director of photography Julio Macat), while filming here before the crew moved to Easton, Md.