Foreign-born newcomers to New York City’s public schools are performing better than native-born newcomers, a New York University study shows.

The working paper by NYU education researchers titled “Do Immigrants Differ From Migrants?” has also deflated any notions that immigrant students tend to do worse in American schools the older they are when they arrive. On the contrary, the findings demonstrated that immigrant students actually do better if they begin their American education in high school rather than in elementary or middle school.

“The foreign born are whizzing by the native born at every level,” one of the researchers, Amy Ellen Schwartz, said.

The study, by Leanna Stiefel and Ms. Schwartz, both of the Institute for Education and Social Policy at NYU, and Dylan Conger of George Washington University, was conducted by comparing immigrant and native-born students who entered the New York City school system at the same age. It found that even without controlling for such factors as language ability, race, and individual schools, immigrants do better.

When those factors were controlled for — allowing researchers to compare similarly situated students — immigrants who arrived in high school pulled out ahead of immigrants who arrived earlier, and even further ahead of native-born students.

Researchers focused particularly on comparing how newcomers do when they move to New York during high school; a previous study of the elementary and middle school levels showed similar trends.

Ms. Schwartz, speaking at an NYU symposium last week, said she and her colleagues had hypothesized that immigrant students “who come late are the ones who are really disadvantaged,” guessing that their lack of language skills, the stress of moving to a new country, and institutional differences between the schools they came from and the New York schools might hurt their graduation rate and performance on tests.

Instead, they found that the foreign born “just do remarkably better,” Ms. Schwartz said.

“We find virtually no evidence that high school entry is particularly harmful for immigrant students,” the study said. “Immigrant students do quite well and high school entrants even better than earlier entering immigrants.”

The study used data from the Department of Education on the performance of about 60,000 students in the New York City public schools who were scheduled to graduate in 2002. Among those students, about 34% were born in other countries.

Researchers found that foreign-born students are more likely to graduate on time than native-born students. They are also more likely to take the SAT, although their scores tend to be slightly lower than native-born newcomers. Immigrants do better on math Regents exams, however.

The study’s findings were borne out recently after a new rating system for city schools highlighted the Manhattan Bridges High School, which serves only recently arrived Hispanic students, as the best-performing school in the city.

Ms. Schwartz said the goal of the study was to separate out the educational effects of being born in another country from the effects of poverty, language, and race.

She noted that the study’s findings continued to show a gap between the performance of blacks and Hispanics and their peers. She also noted that a larger proportion of native-born students are Hispanic, 34%, compared to the proportion of foreign born who are Hispanic, 31%.

The high school study is a part of a larger research project on immigrant performance in New York City schools; the city was chosen because of the availability of data on immigrants.

Ms. Schwartz said further research is required to determine exactly why immigrants do better when they arrive in school later, and why they do better than native-born students. She suggested that one reason might be the special programs for immigrant newcomers at the high school level that are less available for younger students or for students who move to New York from elsewhere in the country.

Another might be that immigrant students who enter the school system in high school are a self-selected group who are enthusiastic about school, she said, while other immigrant students who might do more poorly may choose to join the workforce instead of going to school.