Emilio T. Gonzalez, U.S. Citizenship and Immigration Services director, administered the oath of allegiance to the service members, many of whom had recently returned from the Middle East.
"On behalf of a grateful nation, I want to congratulate you on becoming America's newest citizens," Gonzalez told 146 members of all branches of the military.
President Bush signed an executive order in 2002 making immigrants serving in the military since the Sept. 11, 2001, attacks immediately eligible for naturalization. Before the order, immigrants in the military had to serve three years before they could apply to become citizens.
Since the attacks, USCIS has naturalized 24,745 military service members.
The people sworn in as new Americans on Wednesday hail from 50 countries, from Albania to Venezuela.
Sgt. Vasil Mencev became a citizen 31 years after he first moved to the U.S. as an infant with his parents and sister. The family returned to Macedonia while he was still young, but Mencev came back at the age of 20. He joined the Army, was stationed at Fort Lee in Petersburg and spent a year in Iraq riding a fuel truck in convoys.
Mencev, whose wife and son attended the ceremony, said it felt great to finally fulfill his late parents' dreams.
"They came here to get a better future," he said.