The Saturday that Sara Katherine Paxton took the SAT, at a private school on the Upper West Side, the line of nervous 17-year-olds waiting to sign in snaked nearly halfway through the entrance room. Flustered, a proctor put his hands on his desk and stood up.

“If you have extra time, stand to the side,” he said. Half the teenagers stepped out of line — and, Miss Paxton said, no one batted an eye.

The practice of giving students with learning disabilities more time to take their tests has become so common at top private schools in New York City and across the country that students say it carries nearly no stigma. For everything from the SAT to weekly math quizzes, they say, a growing number of students will get as much as double the standard time allotment, and no one pays much attention.

Disability rights activists describe the trend as an important victory for students with difficulties such as dyslexia and attention deficit disorder, but a small number of students are waging a battle against the accommodations, a struggle that could intensify when the SAT season begins again this fall. Their target audience: college admissions officers, who they say risk being hoodwinked into admitting students with artificially impeccable transcripts.

“Close to half of the students in my grade with extra time are going to Ivy League schools, and they’re all going to some of the top schools in the nation,” Miss Paxton said. “If they can compete at that level, they shouldn’t need extra time.”

The group that administers the SAT, the College Board, used to identify students with special accommodations by placing an asterisk on their score reports, but it stopped the practice after a student who had no hands sued, charging discrimination.

Several admissions officers batted down the concerns. “It’s been a long time since anyone thought those tests reflected anything like a pure measure of achievement,” Harvard’s director of admissions, Marlyn McGrath, said.

The University of Pennsylvania’s admissions dean, Lee Stetson, said he is confident that the College Board has become more vigilant with accommodations since dropping the asterisk. To get accommodations, students must provide both psychological tests and proof that their school acknowledges the disability, the Board’s executive director of SAT program relations, Brian O’Reilly, said.

Mr. O’Reilly said standards have always been rigorous, but others familiar with the process said they have gotten more so as the number of students who receive extra time balloons. The portion of New York State students who took the SAT under “nonstandard” circumstances dropped to 3% last year from 4% in 2005, College Board data show. Nationwide, the percentage in 2006 was 2%. The College Board declined to release data for Manhattan or for New York City.

An independent college consultant based in New York, Bev Taylor, said her clients have paid as much as $10,000 to test their children, and gotten back diagnoses of disorders such as “test anxiety,” without getting approved for accommodations.

A psychologist at the Manhattan firm Behavioral Associates, David Shmerler, said the rush of requests for testing begins when college entrance testing begins. “A lot of people are coming in from high school saying, ‘I was always slow, so now that I’m taking the SAT and I’m completely panic-stricken, I want extra time,'” Dr. Shmerler said. Not all of them will get the diagnosis; panic, he said, is not the same as a disability.

A hunch that not all psychologists are as rigorous is behind the effort to challenge the practice. “Whatever happened to just not being good at something?” Miss Paxton wrote in an article published this year in her school’s student magazine, enraging many of her peers at her Upper East Side private school.

A student who graduated from a Chicago private school this spring, Jeremy von Halle, wrote a speech this year with a similar bent. He wrote it after counting that 25% of his classmates were getting extended time on tests — a number he said was obvious because his school stamps special Post-It notes on the lockers of students who get extra time to inform them where to take their exams.

Titled “Extended Privilege,” the speech condemned accommodations as an unfair advantage and called for an end to timed testing. Mr. von Halle said he planned to deliver the speech to the entire middle and upper school, but administrators blocked it at the last minute, citing concerns he would hurt students’ feelings.

A junior at the Packer Collegiate Institute in Brooklyn Heights, Madison Utendahl, said she has also watched many of her friends receive diagnoses in recent years, but she is responding in a different way. This week, she said, she is spending two days getting tested for a learning disability, at a cost of $1,500. “If it’s going to help me do better on my SAT’s, it’s better to get it over with,” she said.

The stepfather of a law student in Michigan, Robert Wagner, said his daughter made the same decision after watching peers with extra time hoist up the curve by taking as much as 30% more time on their exams. After taking out an extra credit card to pay the $700 testing fee, her grades are improving, Mr. Wagner said.

The head of school at the Saint Ann’s school in Brooklyn Heights, Lawrence Weiss, said that the notion that students are getting accommodations unfairly is a myth. “There are a lot of questions that have been raised about why this student gets extra time and I don’t, and is that fair?” Mr. Weiss said. But he said disabilities are real and should be treated seriously.