It was Homecoming at Bowie State College last week, but the students clustered outside the financial aid office weren't talking about football or what to wear to the dance. They were dissecting, fervently and with intimate knowledge, the cost of attending college. It was a painful subject.

Ronald Toole, a freshman from Parkesburg, Penn., pays about $7,000 a year in tuition, room, board and fees. His federal Guaranteed Student Loan (GSL) covers $2,650; his father took out a personal loan, and Toole pays the rest with summer savings and what he earns dishing out food at the campus snack bar.

Without his student loan, he might have borrowed from his brothers, he said, but "I might have sat out . . . . I probably would have never gotten to school."

As a Maryland resident, Yvonne Thomas pays less tuition, but when she didn't get her federally guaranteed loan this semester and it came time to pay the bill, "I just made it." If she doesn't get a loan next semester, she said, she'll live with her mother in Baltimore and commute to a college closer to home.

For these students, borrowing money to pay tuition is as much a part of the collegiate landscape as Homecoming and finals. They know they will graduate in debt, and they say they'll pay back what they owe. But more than 3 million students before them have failed to repay their college loans, and the federal government, faced with $1.6 billion in defaults, is cracking down.

As a result, institutions like Bowie State College, where the default rate is 40 percent, could be barred from receiving GSL funds, a move that would devastate the school financially and keep out as many as 600 low-income students.

Thomas and Toole will probably be close to graduation by the time the new regulations are enforced. But the changes could have a dramatic impact on younger students who want to attend institutions with high default rates, which often are institutions with high black enrollment, community colleges and for-profit trade schools.

"We can't afford to be eliminated from the program," said Bowie State College President James E. Lyons. "I have to believe we would lose most of those students" receiving GSLs. "It has very serious implications for the institution."

Education Secretary William J. Bennett, citing a 200 percent increase in default costs in five years, announced last week that schools with default rates over 50 percent will be reviewed and, in some cases, barred from receiving GSL funds. Those that have failed to lower their default rates to 20 percent or below within three years will also be subject to expulsion from the program.

Bennett's move was the most far-reaching among several steps the Reagan administration, Congress and the education community have taken to bring down soaring default costs. It was also the action aimed most directly at educational institutions; other efforts have focused on lenders and guarantee and collection agencies. There is wide consensus that schools, hundreds of which have default rates of more than 50 percent, must do their part. Education officials project that the tightened regulation could result in annual savings of more than $700 million. But there is also some concern that the new regulations will force the closure of many institutions and reduce access to education for low-income students.

"We cannot accept solutions that will have a Draconian effect on students, schools or lenders," said Sen. Edward M. Kennedy (D-Mass.). "The Reagan administration proposals appear to make higher education institutions bear a disproportionately large share of the burden in reducing default costs."

Of the 7,295 institutions participating in the program, nearly a third have default rates over 20 percent. Education Department officials agree that some institutions probably will, and should, close down, arguing that high default rates often indicate that students are not receiving a quality education, that they are being accepted with little chance of graduating or gaining employment, or that they are not counseled carefully about their debt.

Officials also dismiss criticism that their actions will hurt students.

"I don't think this is going to mean that any black students are not going to go to college," said Bruce M. Carnes, education deputy undersecretary. "The loans are not going to be taken from them. Even if there were not any black colleges, there would still be 7,100 other institutions they could attend."

Only a quarter of the traditionally black colleges and universities in the country have default rates below 20 percent, Carnes said. But another quarter have default rates between 20 and 30 percent, and should be able to lower their rates before the tightened regulations take effect.

At Bowie State, where 67 percent of the undergraduates are black, Lyons sees a difficult road ahead. "I acknowledge, it's just a shame. There is no legitimate justification for billions of dollars to be in default," he said.

And he is willing to take the steps Bennett has suggested: withholding academic transcripts from students who are in default, looking carefully at incoming students, counseling students about the responsibility of accepting a loan.

"We are going to have to push ourselves into the process," he said. "We're going to work hard at it because the stakes are so high."

Donald A. Kiah, Bowie State's financial aid director, was dubious about the ability of the school to dramatically reduce defaults. Better counseling, he said, "is going to have a positive impact, but I don't think it's going to have that much of an impact. All we do is certify that the student is enrolled. We don't have any idea what type of credit risk that student might be."

The school takes in $1.3 million annually in GSL funds. If the nearly 600 Bowie State students receiving GSLs were no longer able to use those loans, they would be likely to enroll elsewhere, depriving the school not only of the loan funds, but the remainder of the tuition, room and board they pay.

Lyons argued that special consideration should be given to traditionally black institutions and others serving low-income students, who are the most likely to default.

"In the case of schools like ours, there should be a special look at what we're trying to do," he said, rather than a federal policy that is "hung up on an exact percentage."

Carnes said that the department policy will take into consideration whether schools have made progress in lowering defaults, but "we're going to apply the same standards to everybody across the board. The fact is that all students, whether they are black, Hispanic, women, in any particular field, or attending any type of institution, have the same obligation to repay their loans."

That sentiment and the belief that institutions have some responsibility, even though students are months out of school when their loans become due, is widely shared. It has prompted higher education associations to urge their members to work aggressively to track their student defaulters and set up extensive "exit interviews" to inform students of what they owe and how they should go about paying it.

Congress has also stepped up pressure to lower default costs. The Senate included in its trade bill, which is now before the House, a provision allowing guarantee agencies to refuse loan funds to institutions with high default rates.

And in reauthorizing the Higher Education Act last year, Congress required that student loan funds be disbursed in more than one payment, ensuring that a full year's allotment is not lost if a student drops out of school. It has also tightened requirements that lenders exercise "due diligence" in collecting delinquent loans before declaring them in default and turning them over to the federal government for repayment.

The Education Department has also stepped up collection efforts, bringing in $516 million in fiscal 1987, compared with $92 million five years earlier. The department has begun reporting defaulters to consumer credit bureaus, to keep them from gaining credit financing for personal loans or mortgages.

Since last year the department has referred more than 1.5 million default accounts to the Internal Revenue Service, which can withhold refunds against unpaid loans. As a result, $269 million has been collected. Also, federal agencies have begun screening applicants so that defaulters are not hired unless they agree to repay loans.

Even in a climate of concern about default costs, the strict new guidelines announced by Bennett prompted criticism from Capitol Hill and some education groups.

Representatives of the sector probably most affected by the new rules, the proprietary trade institutions, argued that if many secretarial, mechanics and other career schools are forced to close, access to training will be severely reduced for low-income minority students.

Richard Armbruster, director at TESST Electronic School in Hyattsville, was also skeptical that the school could significantly lower its 37 percent default rate. "If you have a student who is eligible . . . you can't say, 'We don't think you're a good credit risk.' "

Among the unanswered questions in the debate over default costs is why so many students fail to repay the money they borrowed. Education officials contend that many are not told explicitly that the money they are receiving is a loan, not a grant.

Lyons believes that defaulters are often those who cannot afford the payments.

"Students are so saddled with loans," he said, describing what he said was a typical graduate who becomes a teacher at an annual salary of $14,000, with college debts of about $20,000. "I feel for the student in that situation."

At the same time, he said, the school must make a "moral appeal" to students to repay their debts, emphasizing that their failure to do so will keep future students from receiving federal aid.

Yvonne Thomas said she will repay her loans, knowing that if she does not, she will jeopardize her ability to borrow later for a home or a car. Howard Brent, another Bowie State student, said he will repay his debt because "it makes me appreciate my education more."

Ronald Toole said he will not only repay his loan, he will help his nephew pay for college. "Our family is close," he said. "We always try to make it easier on the next one coming up."

But Thomas voiced the burden many of the students feel: "You're under 20, and you're in debt already. It seems like they want you so much to stay in college, but they make it so hard; they're driving you away."