The most recent round of reading tests show students attending charter schools in the city outperforming other public schools on reading tests.

Sixty-one percent of charter school students in the city who took the test met state standards, compared to 51% of students citywide. Charters’ performance also seems to be improving at a brisker pace, with the number of students meeting standards rising five points from 56% last year. City schools overall reported a gain of one-tenth of one percentage point.

The city’s 58 charter schools operate outside some of the public system’s constraints, and Mayor Bloomberg and his schools chancellor, Joel Klein, have worked to increase the number of charter schools in the city. In New York, only a small portion of students attend charter schools, but legislation signed by Governor Spitzer this April increased the number of charter schools allowed in the state to 200 from 100.

Of the 58 city charter schools, 42 this year had students take the state’s English Language Arts exam, which is given to third- through eighth-graders, the New York State Charter Association’s policy director, Peter Murphy, said. The tests were given in January and reported by the city and state departments of education last week.

Mr. Murphy hailed the figures as evidence of the schools’ advantages, including their freedom to do things like extend the class day and their obligation to raise test scores or face consequences. When poor performance led Reisenbach Charter School in Harlem to lose its charter three years ago, the act “sent a shiver through the rest of the charter school community,” he said.

His group’s own study found that three-quarters of state charter schools outperformed their districts, a comparison designed to control for regional differences.

A professor of education at Columbia Teachers College who studies charter schools, Jeffrey Henig, cautioned not to draw conclusions from the ten-point difference disclosed in the Sun’s analysis. “Doing simple comparisons across one point in time is dangerous and misleading,” Mr. Henig said. A fair assessment would chart each student’s individual test score gains over time, he said, and would also control for outside factors like poverty, disabilities, and parental involvement.

Mr. Henig said charter schools could get an artificial boost, since they tend to serve more elementary school students, whose test scores tend to be higher. Indeed, city charter schools this year served more elementary than middle school students.

But older students in charter schools performed better than older students in traditional public schools. More than half of charter school eighth graders, 54%, met state reading standards, compared to just 42% citywide. And while less than 50% of sixth- and seventh-graders met standards citywide, in charter schools, 58% of seventh-graders and 61% of sixth-graders did.

A cofounder of the pro-charter group Democrats for Education Reform, Charles Ledley, suggested charter schools should be judged by the performance of their oldest students, who have been in the schools longer. At the Leadership Village Academy in Manhattan, for instance, only 50% of entering fifth-graders this year met reading standards. But 79% of sixth-graders did — a number that towers over the rest of the District 4’s showing, 35%. Few other charter schools, however, showed trends that dramatic.

Mr. Henig also pointed to the problem of selection bias. New York City charter schools have the same portion of low-income students as the rest of the city, 74%, more black students — 66% compared to 33% — and fewer Latinos, a department of education spokeswoman, Melody Meyer, said. But Mr. Henig said research shows teachers sometimes shuttle a disproportionate number of troubled or ambitious students into charters. “The question is, how do you sort that out?” he said. “You need better data.”

Neither New York City nor New York State publish data on individual student gains.