Washington developer Samuel G. Rose, a stocky man with unruly hair, yelled into the speaker phone on his desk, which was covered with stacks of paper and pictures of his safari outings to Kenya and bone fishing trips in Florida. "You can't just walk off the job because you don't like it," he said into the phone. He leaned his leather chair forward, put down the art catalog he was flipping through and said, "What the hell are you thinking?"

For 10 minutes he berated Marcus Sykes, a 20-year-old Bowie State University junior, who was on the other end of the call. Rose hired Sykes to work this summer at one of the large office buildings his company owns near Union Station. Sykes was supposed to sweep the floors, clean the windows, accept and deliver packages, change light bulbs, and smile at passersby. But after less than an hour on the job, Sykes quit, saying he could do better than the $8.75-an-hour job Rose was offering.

Sykes tried to appease Rose by telling him about his 3.75 grade point average last semester. But Rose responded: "Good grades are all fine and good, but you've got to have work ethic and principles. You have to carry things out."

Rose, 68, abruptly ended the call. Then he announced to those within earshot in his office that he would continue to pay part of Sykes' tuition this fall.

Sykes and with 30 other students, are learning about Rose's idea of philanthropy. Rose has given $589,400 to his alma mater, Dickinson College in Carlisle, Pa., to set up a fund to help minority students pay for their college costs. He has also helped other students like Sykes.

"It's not enough to just cut checks and throw money at them," Rose said. "You've got to have somebody stand up for you and to push you a little bit."

"He can be really demanding," Sykes said. "But he's helping people out. He's giving back."

Sykes's mother, Janet Jefferson, 42, a Pentagon secretary who is going to night school to earn her associate degree in business management, said she is thankful Rose has taken an interest in her son. "He's taken Marcus under his wing," she said from her Fort Washington home. "It's hard when you're a young male and trying to make it in the world."

Stephanie Lawrence, 21, of Upper Marlboro who said Rose has paid about 13 percent -- or $20,000 over four years -- of her college costs, said that she admires how Rose has built up his business and that she has gotten used to his gruff ways.

"Even when he's barking at you, I don't get rattled," said Lawrence, who graduated in May. "I like to think of myself as a tough person."

Rose grew up in Baltimore, the son of an insurance salesman and a housewife. He went to Dickinson College in rural Pennsylvania on a lacrosse scholarship, and after graduating in 1958, he sold insurance and then taught sixth graders at a Baltimore school. He attended University of Baltimore law school at night, graduating in 1962.

Frustrated with the school system's bureaucracy, he went to work for Rouse Co., a Columbia-based developer. After 12 years, he left to work for other developers, and in 1980, he started Greenebaum and Rose Associates. His partner, Stewart Greenebaum, runs the company's Baltimore office, and Rose runs the D.C. office in Friendship Heights.

The firm first made millions of dollars by buying land, getting it rezoned, putting in streets and sewers, and then selling the lots to home developers. It then moved on to buying and selling office buildings.

In 1983, Rose bought land near Union Station, when few other developers were interested in that area. Over the past two decades, he has built a million-square-foot complex there, which houses such large tenants as CNN, the Federal Energy Regulatory Commission, the U.S. Department of Education, and Blue Cross and Blue Shield.

As his wealth accumulated, Dickinson College asked him for donations, but he was reluctant. When a new college president, William G. Durden, asked him five years ago why he wouldn't give money, Rose said it bothered him that there were so few non-whites attending the college. Four percent of the college's 2,200 students were minorities in 1999. "It was such a lily-white campus when I was there," said Rose. "And the world's just not like that."

Rose, who is Jewish, said he grew up in a white working-class neighborhood. Most of his high school and college friends were white. But he said he "empathized with the underclass. Jews were the underclass for hundreds of years." He said he wanted to help "lift the next underclass." He believed that education was the best way. "If you give somebody education, they could change their life," he said.

As he grew older, it particularly bothered him that his alma mater had apparently made so little effort to recruit non-whites. He told college administrators he would not make donations until they came up with a plan to significantly increase the number of minority students.

One problem, college officials told him, was that minority candidates sometimes could not afford the roughly $38,000 annual cost. Even those who qualified for scholarships often had gaps in their financing, and they were wary of taking out personal loans because of the large debts they would face. Rose agreed to pay part of the tuition for some of those minority students.

"His money has made an enormous difference in our ability to attract students of color here," said Robert J. Massa, vice president for enrollment and college relations at Dickinson, who was has made it one of his goals to increase minority enrollment. Massa said 11 percent of the students are minorities, and this fall the college expects its incoming freshman class to be 14 percent minority.

The minority students who receive money from Rose are selected by a team of Dickinson administrators headed by Massa. The group reviews grades, high school class rankings, SAT scores and ability to pay. Rose said he doesn't always agree with the administrators' choices but hasn't rejected any of the students they have recommended. The amount of assistance varies, but on average each student gets between $2,500 and $4,000 a year. Rose prefers to help students from the D.C. area, but has also funded those from Philadelphia, Baltimore and New York.

Rose said he hosts dinners at Dickinson and brings executives from Washington to meet the students and talk about how they became successful. He also offers the students summer jobs. This May, the first group of Dickinson students who got money from Rose graduated. Lawrence was one of those students.

She has worked three summers and every winter and fall break at Rose's office as a secretary. She takes rapid dictation and answers phones. Rose makes her use her fluent French when he's buying French art. One recent summer afternoon Lawrence raced around, taking dictation and orders from Rose. "Get this New York art guy on the phone for me too," Rose ordered her. "And get the guys to open the crate again so I can see the thing," he barked.

"He can be gruff," Lawrence said. "But he's also funny."

"She's the smartest SOB I've ever met," said Rose, as he dictated a letter to her. "She takes shorthand and runs circles around everybody in this office."

Lawrence graduated in May as a biology major and was accepted at six of the 11 medical schools she applied to, including Jefferson Medical College at Thomas Jefferson University in Philadelphia, Tulane University in New Orleans, Temple University in Philadelphia and the University of Connecticut.

She said Rose may help her with those costs too. "Mr. Rose told me to talk to him further about paying for my medical school," she said. "We've discussed it. I'm sure he'll contribute. He knows that's what I want to do." She said, however, that he keeps hinting that maybe she should also consider becoming a real estate broker because she's good with numbers. "He thinks I'm really smart and I could succeed doing a lot of other things," she said.

Sykes has been more of a problem for Rose because Sykes hasn't followed his advice, something Rose is unaccustomed to and finds frustrating. Yet the relationship between the two continues. Rose met Sykes last summer, when Rose had a summer barbecue for students. Sykes accompanied his girlfriend, who was involved in a program Rose supports that prepares young people for college. Sykes introduced himself to Rose and a few weeks later visited Rose in his office.

Sykes told Rose it cost $14,000 a year for him to attend Bowie State. Even after loan and grants, he was short. Rose put up $2,000 so he could attend. During the semester, Rose would call Sykes's cell phone and talk to him as he hopped between classes for his sociology major.

"He'd ask how I was doing, if I needed anything, and then tell me what he thought I should do," Sykes said. Sykes shared his worries about trying to raise his 2-year-old son. Rose told him the best thing he could do for his son was to get an education.

"I consider him someone I could look up to," Sykes said. "He's a very smart guy."

Rose said he desperately wanted Sykes to leave his parents and son and attend Dickinson College. "I felt that he would do better by getting outside of this area. If he got out of the hood and got away from his parents and understood what it's like to live by yourself -- that's where I was coming from. But why should be believe me? Who the hell am I?"

Rose drove Sykes to Dickinson last spring to check it out. He introduced Sykes to the college president, who invited the young man to apply. Sykes applied and was accepted. But he had second thoughts when he was told he would have to push back his May 2005 graduation by a year because not all of his credits would transfer. And he worried about leaving behind his young son.

He eventually rejected the offer. "I wanted to go to Dickinson, but I couldn't stand being away from my son for so long," Sykes said. "I made a mistake of having my son at a young age, and now I have to accept the responsibility.

"I couldn't go away. Mr. Rose didn't think it was a good decision," Sykes said.

Sykes's actions were a huge disappointment for Rose. "He left my summer job, and I tried to get him to transfer to Dickinson but he wouldn't," Rose said. "He's kissed off both opportunities I gave him."

Asked if he will continue to help pay Sykes's tuition, Rose said, "I promised I'm going to help him through school. Whatever he needs to get through Bowie State, I'll be there."

After quitting his job with Rose, Sykes worked at a video rental store for a month and then in June began a $6-an-hour internship at the Palmer Park police station in Prince George's County to prepare for a career working in law enforcement.

Rose frowns at the mention of Sykes's new job.

"He couldn't figure out that he would have made contacts that would have helped him in life if he had just worked one summer for me in my company," Rose said. "He's got a little bit too much pride. His attitude is, 'Pay my tuition but I'll make my own decisions.' I hope he gets to do what he wants, but there's nothing like having somebody to open doors for you."

Sykes said he's rarely bothered by Rose's sometimes sharp remarks.

"He's been there for me and he's done a lot," Sykes said. "He's trying to help me as much as he can. Yes, he's demanding but I don't see anything wrong with it. That's just him. It doesn't bother me. He pushes you."

Marcus Sykes, below, is one of the students who is getting tuition aid -- and a lot of advice -- from developer Samuel G. Rose.Stephanie Lawrence graduated from Dickinson with the tuition help of Samuel G. Rose and is working in his office for a fourth summer.