Mayor Bloomberg yesterday announced the largest six-month decline in homelessness since 1990.

The administration released a plan outlining its strategy for ending chronic homelessness last June. At the time, the average monthly homeless census was up to 37,462 individuals. By this May, the agency’s average monthly count was down more than 3,000 to 34,080.That marked a decrease of 9%.

The average monthly census for homeless children in May 2004 was 15,766, according to the Department of Homeless Services. This May, that was down to 13,770 for a decrease of 13%.

“A year ago last week, our administration launched an ambitious plan to end chronic homelessness in New York City. We set a goal of decreasing by two thirds the number of homeless men, women, and children living in city shelters and on city streets by the year 2009,” Mr. Bloomberg said at a City Hall news conference, standing beside the commissioner of the Department of Homeless Services, Linda Gibbs. “We’re well on our way, I’m happy to report, to reaching that goal.”

In the past year, the city has created 3,454 units of “supportive housing” for people at risk of homelessness. It placed a record 7,078 families into permanent housing. That is 11% more families than were placed in permanent housing in 2003, and 67% more than in 2002.

Mr. Bloomberg, who is seeking reelection this year, said the city’s “fresh approach” enabled the Department of Homeless Services to start producing positive changes in the same way that his administration’s creative solutions have tackled other urban challenges throughout the five boroughs.

“People thought that we were biting off more than we could chew to say that we could reduce homelessness by two thirds,” he said. “I think people thought that this was one of these problems, like fixing the school system, that there really wasn’t any solution for, and that, when we went out and set specific goals … we were not acting prudently for our own safety.”

He continued: “I’ve said to all of the commissioners we’re not supposed to be doing what is politically correct. We’re supposed to be doing what we were hired by the public to do, and if we set ambitious, aggressive targets, the results will be better.”

The mayor announced yesterday that the city would close its largest shelter, the Carlton House Residence in Queens, which was opened July 4, 2002, in what Ms. Gibbs described yesterday as a “Band-Aid” response to record levels of homelessness.