WASHINGTON -- There are packing boxes now in her spacious Treasury Department office overlooking the White House, and there will soon be a new treasury secretary overseeing gun issues and, with a new administration, probably a new gun-control policy. 

But as she gets ready to leave her obscure job as senior adviser for firearms policy coordination to the under secretary of the treasury for enforcement, Susan Ginsburg can take satisfaction that she has presided over what some law- enforcement officials and academic specialists call one of the most important accomplishments of the Clinton administration. With no public recognition, she has helped transform the understanding of how criminals and juveniles get guns, an achievement that has provided new ways to crack down on the illegal firearms market. 

"To put what she did in perspective, it's like saying that up till five years ago, nobody had been doing any drug enforcement," said David Kennedy, a senior researcher at the John F Kennedy School of Government, at Harvard. 

Philip J. Cook, a professor of public policy at Duke, turns to the Bible for a comparison. "Susan reminds me of the story of the miracle of the loaves and fishes," he said. "She may not have had a staff," he said, and she worked under the shadow of the National Rifle Association and its allies in Congress, but she essentially created a new federal policy out of little more than  some abstruse academic thinking. "She has really been one of my heroes." 

At least as remarkable, in contemporary Washington, Ms. Ginsburg has never been quoted by name in a newspaper or appeared on television. Her anonymity is such that when asked his reaction to her work, even Bill Powers, the chief spokesman for the N.R.A., said he had never heard of her.  

That is precisely how Ms. Ginsburg, wary of gun-control politics and modest as well, has wanted it. "I've been very disciplined about not seeking publicity," she said. Even when she knew this profile of her was being written, she insisted in a cascade of messages that the real credit should go to Treasury Secretary Lawrence H. Summers, people at the firearms bureau and the academic researchers who first suggested to her the possibilities of gun tracing. 

MS. GINSBURG, 47 and divorced, says she does not know where she will be working next. She likes to garden, read and run marathons. But her idea of a good weekend has been to spend hours preparing a report on tracing crime guns. 

She was born in Washington and is a graduate of Bryn Mawr and the University of Pennsylvania Law School. She feels a need, she says, to serve "the public good," an inclination she admits can lead to being labeled "naïve or disingenuous today." 

She inherited this, she said, from her father, David Ginsburg, who as a young lawyer from Huntington, W.Va., went to work for the New Deal administration of President Franklin D. Roosevelt and became a clerk for a Supreme Court justice, William O. Douglas. Mr. Ginsburg was a co-founder of Americans for Democratic Action and the author of the Kerner Commission report on civil disorders, which warned that the United States was in danger of becoming two nations — one black, one white. 

Ms. Ginsburg had no special interest in gun control when in 1995, as an official at the Treasury Department, the firearms bureau's parent, she was invited to an academic conference in Santa Fe, N.M., on youth violence.  

It was there that scholars like Mr. Kennedy and Professor Cook explained to her their new findings suggesting that criminals were buying their guns, directly or indirectly, from licensed dealers, rather than stealing them. 

"I became an accidental convert," Ms. Ginsburg said. "It was my job to translate their ideas into policy," some of which she did in telephone calls with them lasting up to 10 hours, without an interruption for a meal. 

Ms. Ginsburg then put the resources of the firearms bureau to work, greatly increasing the number of crime guns it traced. By now, the agency has recruited 50 cities and 6 states to trace all guns they recover in crimes.  

The research has produced some crucial findings. For example, it has shown that only a small fraction of dealers, 1.2 percent of the total, accounted for more than half of crime guns traced in 1998. At the same time, it has underscored the scholars' initial discovery that criminals and juveniles want only certain guns: high-powered semiautomatic handguns of a kind widely available only in the last few years. 

Contrary to the experience of earlier years, when the N.R.A.'s supporters in Congress kept the firearms agency's budget small, Ms. Ginsburg came up with a way to diffuse Congressional opposition. By focusing on criminal conduct by scofflaw dealers and criminals' acquisition of guns, she found a middle ground between gun-control advocates and the rifle association that has broad political appeal. 

The result, she said, is that in the budget passed by Congress last week, there is money to hire 500 new ATF agents. That will be the first real expansion in agent staffing since the bureau was created nearly three decades ago.