For five long months, Doris M. Meissner was engulfed by the Elian Gonzalez case.

As commissioner of the Immigration and Naturalization Service, Meissner was the first to decide that the 6-year-old Cuban boy should return to his father after his mother died in an attempt to reach Florida. Meissner and her boss, Attorney General Janet Reno, were berated on talk shows, cursed by Cuban American activists and, when armed INS agents seized Elian, pilloried in Congress.

Most would consider this an ordeal. But to Meissner, being thrust into the middle of a political firestorm "was one of the most satisfying experiences professionally that I've had.

"It was a team effort that worked extremely well," she said last week in her office on the outskirts of downtown Washington. "I didn't come here to work against 30 years of practice when it came to Cuba and Castro. But the case was what it was, so we rolled up our sleeves and said, 'Let's do it right.' "

The Elian saga wasn't the only political gale to buffet Meissner, 59, who ended her seven-year tenure as head of the INS Friday. Her term was plagued by scandals and missteps as she tried to remake one of the government's most troubled agencies. At the same time, the INS was coping with one of the largest waves of immigration in U.S. history; 1 million or more immigrants arrived annually during most of Meissner's term.

Meissner, who also held immigration posts in the Carter and Reagan administrations, oversaw a doubling of the INS work force to 32,000 employees, and a tripling of the agency's budget to $4.3 billion. She earned praise from immigrant advocates, and even some foes, for bringing professionalism and expertise to an agency that was known for neither.

Meissner cut down on backlogs in the INS's troubled asylum system, implemented a crackdown along the Mexican border and worked to speed approvals for legal immigrants seeking citizenship. Just last week, the INS announced that the wait for naturalization had declined from more than two years to less than nine months, while the application backlog had dropped to 800,000 from a high of nearly 2 million two years ago.

"She inherited a badly structured, demoralized agency at a time when the immigration debate was getting red hot," said Frank Sharry, executive director of the National Immigration Forum, an advocacy group. "She's performed admirably and effectively in an impossible job."

Meissner, who will return to a post at the Carnegie Endowment for International Peace, said the INS "is not only a significantly bigger agency, it's a significantly better agency."

But Meissner frequently ran afoul of advocates on both sides of the immigration debate and often raised the ire of critics in Congress. She fought unsuccessfully against 1996 legislation that expanded the list of crimes punishable by deportation and helped derail attempts to split the INS into separate enforcement and service agencies.

Last year, Rep. Lamar S. Smith (R-Tex.), chairman of the House immigration subcommittee, called for her resignation amid reports that as many as 1,500 nonviolent criminal immigrants were set to be released because of crowding in detention centers. The INS scrapped the plan and Meissner declined to step down.

A naturalization drive that mistakenly allowed hundreds of criminals to become citizens because of flawed background checks arguably caused Meissner's worst moments. Smith and other GOP leaders alleged that the Citizenship USA campaign, which processed nearly 1.3 million new citizens before the 1996 elections, also was part of an effort by the White House to pad the rolls of Democratic voters.

A Justice Department report dismissed political motives on Meissner's part, but lambasted the INS for a malfunctioning fingerprinting process and a computer system so antiquated that officials couldn't determine exactly how many applicants they had.

T.J. Bonner, president of the National Border Patrol Council, the union that represents most of the INS's 9,100 border employees, said, "We would have to give [her] a failing grade as commissioner." He said that many agents are demoralized and that Meissner should not be credited with increasing the agency's manpower and equipment.

The Federation for American Immigration Reform, an anti-immigration group, said last week that Meissner's resignation was "long overdue and welcome."

"Everywhere she closes a door," Dan Stein, the group's executive director, said of Meissner's attempt to stem illegal immigration, "she opens a window."

Meissner soldiered on through the political crises even as she weathered a personal one. In 1996, her husband, assistant commerce secretary Charles F. Meissner, died in a plane crash in Croatia that also claimed the lives of Commerce Secretary Ronald H. Brown and 31 others. Meissner has two grown children.

The daughter of German immigrants who made their way through Ellis Island, Meissner said her parents' experience helped shape her philosophy. "The fear of not measuring up is universal in the immigrant experience," she said. "I think I have understood that and tried to make it better."