Elite preparatory schools have traditionally sent disproportionate numbers of their graduates to top colleges, but a new study concludes that reputable alma maters may actually hurt students when it comes to college admissions.

In a study out this month in the Sociology of Education journal, City University of New York sociology professor Paul Attewell found that while top students at elite high schools benefit from a competitive environment, students in the middle of the class can lose college admissions spots to similarly or less qualified applicants from other high schools.

Attewell also wrote that top high schools’ grading and application policies harm talented students at the expense of their higher-ranked peers.

Harvard Director of Admissions Marlyn McGrath Lewis ’70-’73 said the College’s admissions office takes such concerns into account when selecting a class.

“You can imagine we’re very sensitive to this,” McGrath Lewis said. “Students who are in competitive elite schools might seem to be underestimated in the process because they may be in the middle of their class, but we do not discriminate against someone who may be in the middle of the class.”

McGrath Lewis said the number of applicants admitted from elite high schools varies annually, and that the admissions process at the College aims to fill a class with the most talented people, regardless of class standing and school.

Stuyvesant High School in New York City, a magnet school with nearly 3,000 students that sent over 20 graduates to Harvard last year, was one of the schools whose college placement data and SAT data were used in Attewell’s research.

A Stuyvesant spokesperson declined to comment for this article.

But concerns raised in the study are very real to college counselors in the nation’s private preparatory schools, according to Stephen M. Manella, director of college counseling at Greenwich Academy in Connecticut.

“That [type of] study is the reason that many private schools do not rank their students,” Manella said. Greenwich Academy, whose graduating class is usually about 50, prefers to rely on recommendation letters written by teachers who have closely followed students throughout their high school careers, rather than providing class rank for college applications.

Manella also said the study’s contention that attending an elite school may harm a middle rung student is misleading.

The high number of qualified students is often used as an explanation for the high proportion of good grades at top colleges, Manella said. The same can be true at secondary schools.

“People will talk about the Ivies, about how the lowest grade is B, and the argument is that if you look at what these kids achieve before they even get in the door, it makes sense,” he said.

Jennifer Graham, who is associate director for college counseling at Buckingham, Browne & Nichols, a preparatory school in Cambridge, says that while students at elite high schools have to worry about competing against their classmates more than their public school counterparts, the middle of the class benefits from attending a competitive school that provides them with a rigorous curriculum.

“I think many selective colleges look at students in school groups, and students are competing against one another,” Graham said. “But the opportunities that our middle of the class gets serve them pretty well.”