Warren A. Lewis, the new head of the U.S. Immigration and Naturalization Service's Washington office, likes to refer to a statistic to describe his approach to the job: In only 18 months in office, he has reprimanded, suspended or otherwise disciplined more employees than his predecessors had in the last several years.

As a result, he says, an office once saddled with a reputation for rude workers, long lines, inefficiency and even corruption has begun to provide better service to the hundreds of thousands of immigrants living in the District and Virginia who seek citizenship, green cards, work permits, visas or other benefits.

"We had to change our overall attitude and the way we do business and be more attentive to the needs of the customers," Lewis said in a recent interview, explaining why he has disciplined more than 20 employees--including supervisors--for offenses such as rudeness, unprofessional behavior, inattention to duties and even absences from work.

"I believe that personnel is our biggest asset. Unfortunately, at times, there's an attitude: 'I work for the government, and you can't do anything to me.' That's unacceptable," he said. "The majority of our employees are good employees, but a couple of bad employees can do a lot of damage."

Local immigration lawyers, long frustrated by the performance of Washington's INS office, especially compared with its counterpart in Baltimore, acknowledged that Lewis has made a difference.

"I think he's working very hard to improve the customer service, and, yes, it has gotten better," said Mary Ryan, president of the local chapter of the American Immigration Lawyers Association, adding that there remains much room for improvement.

Michael Maggio, an immigration lawyer who once publicly compared the Washington INS office to "Dante's rings of hell," also praised Lewis.

"I think Warren Lewis is doing a fabulous job," he said. "He was given one of the toughest jobs in the immigration service, an office that has been grossly underfunded, in a terrible building, where staff morale has been at an all-time low . . . and he increased morale, increased efficiency and productivity, and made the office much more customer friendly."

Lewis, 46, who is the brother of the District's U.S. attorney, Wilma A. Lewis, accepts the plaudits with a little smirk--and the satisfaction of a bureaucrat who has endured his share of criticism in the past.

Lewis, a native of the U.S. Virgin Island of St. Thomas, began his career there more than 25 years ago after taking a civil service exam and finding a job as an investigator for the INS. He worked his way up the ranks, serving in different capacities in Dallas, Houston and the agency's Washington headquarters.

From the start, Lewis said, his goal was to be named head of one of the agency's 36 district offices. He applied repeatedly for openings. But despite high performance reviews, the agency turned him down repeatedly.

Lewis, who is black, responded by filing a discrimination complaint against the INS and leaving for a job with the Federal Aviation Administration. Shortly afterward, in 1993, 19 black INS agents in Los Angeles filed a similar complaint that grew into a class action on behalf of all black immigration officers. It was one of the largest racial bias cases ever filed against the federal government.

A year later, INS Commissioner Doris Meissner selected Lewis to head the INS office in Newark. At the time, he was only the third black agent ever appointed to head a district office.

It was the job of his dreams, he said, but it soon turned into a nightmare. In June 1995, INS detainees rioted at the Esmor Immigration Detention Center in Elizabeth, N.J. Twenty people were injured as detainees took over a building and held two guards hostage for five hours before police broke through their barricades.

The INS eventually confirmed allegations of physical and psychological abuse of detainees by guards at the detention center, which was run by a private company. The agency blamed the company for repeated coverups of problems but also criticized its Newark office for failing to monitor the center properly. Lewis was singled out for blame by some in Congress.

About the same time, Lewis also found his office in the middle of a criminal investigation into its workings. He said he had noticed signs of corruption soon after taking the Newark assignment.

Lewis brought his suspicions to his superiors and to internal investigators at the Justice Department, as well as to federal prosecutors in New Jersey. In 1996, the office's No. 3 official, John Lonergan, was convicted of charges of taking bribes and falsifying documents to help immigrants enter the country illegally. By then, the INS had replaced Lewis as the head of the Newark office and demoted him to deputy director of its Baltimore office.

Lewis thought he was being punished for exposing corruption, and he filed a complaint under the Federal Whistleblower Protection Act. "My life became miserable," he said.

The complaint was resolved when Lewis was appointed to head the Washington INS office, and INS officials said they consider him a "member of the INS team." But he said he still thinks some agency officials are out to make his life difficult, citing the months he has waited for approval to fill key vacancies.

"The service is saying, 'Let's move forward.' That's what they're saying. But I'm having difficulty getting the support to help me take this district where it should be," he said. "I think we're doing a lot of things better, but there's a lot more we can do."