Mark Vogel, ex-jock and former Peace Corps volunteer, hasn't changed much since he hit the big time in Washington area real estate development, his friends and business associates say. Just look at the way he continues to dress.

"I keep threatening to buy him a clip-on tie," said Glenn T. Harrell Jr., the influential Prince George's County zoning lawyer who is one of Vogel's attorneys and advisers.

"He'll give a presentation at a meeting, and he almost looks like he's unraveling," Harrell said, laughing. "His tie comes loose and goes over his shoulder, one sleeve is up around his elbow. I say, 'Man, I should have left you back at the office.' "

Like Prince George's, the county that produced him, Mark Vogel, 39, has turned a rather quirky, underdog image into recent success in the brokerage and development field.

Also like the county, Vogel defies easy labels. Once a middle-class child without connections and an uninspired college student, he has barreled his way to success as one of the area's dozen top developers. He currently has 30 projects totaling $1 billion in seven Maryland and Virginia counties, including the $400 million Bowie New Town Center and a share in the massive PortAmerica project.

He has made profitable friendships with the wealthy and powerful, yet three of his top executives are childhood friends of 30 years with whom he has built and shared his successes. He recently opened a chic champagne bar in Georgetown, yet he is known among friends for his chronic inability to keep his shirttail tucked in and for his biggest dream, to own a sports franchise.

And, although he left his Peace Corps post in Africa with an unabashed vow to make money, for the past three years he has quietly sent money back to the Third World.

Vogel has raised more than $150,000 from the Washington land-development community to build dams in the drought-stricken villages of West Africa.

"Mark is -- how do you describe him? -- he really doesn't bring with him any of that Madison Avenue stuff," said C. Payne Lucas, executive director of Africare, a Washington-based nonprofit agency that works to improve life in rural Africa and is constructing the dams. "He's genuine."

"If I didn't know him, I'd probably think he was a bartender," Lucas said. "Yeah, he reminds me of a good ol' bartender. Same ol' necktie every night."

Vogel is sitting for an interview in his nondescript office at the Watergate complex -- not behind the desk because that isn't his style, but in a side chair with his legs stretched out. In five months, he and his staff of 50 employes will move to new headquarters in Bowie, to a floor of the $14 million, white brick-and-glass office building that is the first entry in his biggest project yet, the New Town Center.

On this day, however, he prefers to talk about "Project Water" and the three dams that have been built in Burkina Faso, formerly Upper Volta. He shows off a small metal pin that was designed by his father, Don, a jovial former advertising consultant who now works with him; it is shaped like the African continent with the words, "Give a Dam" inside. Vogel has dispensed hundreds of the pins to architects, lawyers, landscapers, appraisers and plumbers.

"Some people, I get the opportunity to sit down with them and show them photographs and get them emotionally involved," he said. "Other people, I don't have a prayer doing that, so I just say, 'Hey, we just made a deal. Come on, give me a check.' "

Vogel, who concentrated on sports while growing up in Beltsville, never considered himself much of a do-gooder. At the University of Maryland in College Park, where he half-heartedly majored in criminology, he worked two jobs that perhaps early illustrated his bent for the unexpected -- as a cement finisher and as an aide to Sen. Philip A. Hart of Michigan. He joined the Peace Corps in 1971 "mainly to stay out of the Army," he said, and was assigned to a rural village in Liberia.

"I was way over my head," he said. "I guess my title was construction consultant in charge of getting some projects completed, but I ended up teaching kids how to play basketball. I can remember thinking, 'There's so much I could be doing over here I'm not doing.' I really felt guilty about it."

He vowed to go home, make lots of money, and someday try to make amends. By the time he was 25, he had found his talent for deal-making and was earning $200,000 a year selling apartment projects for a D.C. brokerage firm. In 1976, he left to start his own company.

"I can remember I made a lot of money and they were still coming and telling me I should dress better and comb my hair better," he said. "The real fun is when you don't have anything and you make a deal. It's like a sport, you're an underdog."

He was a tenacious underdog, and he had a certain refreshing charm. "I've thought about it, and the reason I made deals back then was that certain people, especially maybe an older person with a lot of money, would look at me and say, 'I'm going to give this guy a chance.' "

He also was willing to take big risks. He didn't shrink at putting up nonrefundable deposits of several hundred thousand dollars on properties, even when he wasn't sure where he would get the money to complete the deal.

"When I met him about five years ago, he still hadn't arrived," said Frank Lucente, a leading developer in Prince George's County for 22 years. "He has a young-looking face -- I always thought of him as Dennis the Menace. He was friendly, a little impulsive, willing to work hard, but some people said, 'Who is this guy?' I did a lot to help him and he didn't forget that."

Vogel's first major excursion into Prince George's County, where 70 percent of his work is now centered, came about five years ago. He bought 63 acres for $1.55 a foot in Oxon Hill near the future site of the PortAmerica project, Lucente said, then promptly sold 37 of the acres at $4 a foot. "It was one of his first big successes," Lucente said.

One deal led to many. Now, among other things, Vogel is developing a $300 million office park in Frederick. He is about to announce plans for the development of "a Reston-type project," he said, on 2,000 acres on Rte. 301 near Bowie. With the $125 million shopping mall that forms the core of the New Town Center, he may be remembered as the man who brought Saks Fifth Avenue to Prince George's County.

"When I have an appointment with Mark, I like to set aside a couple of hours," said Peter O'Malley, a Prince George's lawyer who is a former county Democratic leader and former president of the Washington Board of Trade.

"I can learn from him," O'Malley said. "There's an excitement about him that keeps me fresh. This business gets repetitious."

There are a few Mark Vogel stories, but almost none of them comes from Vogel himself. He is reluctant to trumpet any details about his deals. ("It might make the sellers feel bad, you know?") About his home life, he said that his wife's name is Judy, they have two sons, ages 3 and 2, and they live in Potomac in a house "that disappoints my friends, but don't get me wrong, it's a nice house."

Loyalty is the watchword in his company. Three of his top executives are Prince George's County natives who grew up with Vogel, played on the same high school athletic teams and attended the University of Maryland with him. A former bartender who was always friendly to Vogel now works as one of his leading brokers; a former car salesman who treated Vogel well also joined the company.

The Bowie New Town Center, essentially the never-before-built downtown core of the third-largest incorporated city in Maryland, is their biggest and riskiest project to date; it also represents Vogel's first full plunge into not just brokering, but also developing, a property.

"At this point, we feel pretty good about the way things are going," said Richard Logue, the outspoken mayor of Bowie. "Vogel's a very ambitious, intense young man who's sometimes a little antsy. He's the kind of guy who goes, 'Hey, you've got my word, why don't you trust me?' It's not that we don't trust him, it's just that we only get to do this once in Bowie."

Vogel views the project in characteristic fashion.

"People say, 'Do you realize what's happened to you in the past couple of years?' But I don't look at it that way. I still have something to prove."