Scoppetta was named by Mayor Michael Bloomberg just three months after the attack that killed 343 firefighters who rushed to the burning World Trade Center towers and as thousands were retiring. In a letter to staff Thursday, Scoppetta said he was leaving to pursue teaching opportunities.
Scoppetta said he took the fire department job because he wanted to help the city recover from the tragedy.
"The biggest challenge was to begin rebuilding the ranks while simultaneously learning the lessons of Sept. 11 and preparing to respond to another attack," he said in his letter.
Under his tenure, the nation's largest fire department hired more than 6,000 firefighters, enhanced radio communications in underground facilities and high-rises, which had been a problem during the Sept. 11 attack, and better trained the rank-and-file on how to respond to large-scale attacks. Since the attack, five times as many firefighters and emergency medical personnel now have advanced training, Scoppetta said. The department also made many technological improvements.
"The indisputable fact is that today's FDNY is, without question, better prepared, better trained and better equipped than ever before," he said.
Scoppetta saw his share of tough times at the fire department, including a 2007 fire at a condemned toxic skyscraper at ground zero, where two firefighters died.
Three fire officials responsible for inspections and safety lapses at the building, which was being demolished, were reassigned. Bloomberg said some of the department's failures there were "troublesome."
It was also under Scoppetta that the city closed six firehouses in 2003 to save money. Firefighters, union leaders and residents in those neighborhoods protested the closings and went to court to stop them.
Scoppetta battled regularly with the Uniformed Firefighters Association of Greater New York, which represents 9,000 firefighters.
"The Scoppetta years were not kind to the Fire Department of the City of New York," said the union's president, Stephen Cassidy.
Civilian fire fatalities increased in the 2003 and 2004 fiscal years, topping 100 per year, but have come down steadily since then. There were 78 civilian fire fatalities in the 2009 fiscal year, which ended in June.
Fire response times also have improved, to a citywide average of 4 minutes, 5 seconds, even though the department had to cut back on hiring during the economic downturn.
Scoppetta said in his letter that the department launched a successful minority recruitment campaign. But a judge ruled in July that the city discriminated against minorities in its hiring of firefighters, causing blacks and Hispanics to comprise only 10 percent of the fire department's work force even though most city residents are minorities.
Scoppetta has 47 years of public service to the city, but was never a firefighter. He was the commissioner of the Administration for Children's Services before his post at the FDNY. He also was an attorney and served as deputy mayor for criminal justice and commissioner of the city's department of investigations in the 1970s.
Bloomberg said the department's performance has been "remarkable" under Scoppetta's leadership.
"Nick Scoppetta has always been a person that you can turn to in a crisis," Bloomberg said. "When the city's child welfare system was in systemic failure, Mayor Rudy Giuliani turned to him to fix it. And when the FDNY needed someone to oversee its recovery after 9/11, I couldn't think of anyone more qualified for the job. As he embarks on plans to teach and write, I thank him and wish him well."
Scoppetta graduated from Brooklyn Law School in 1962 and was born on the Lower East Side.
Associated Press Writer Sara Kugler contributed to this report.