He steered into the high school parking lot, clicked off the ignition and scanned the scraps of his recent weeks. Crinkled chip bags on the dashboard. Soda cups at his feet. And on the passenger seat, a rumpled SAT practice book whose owner had been told since fourth grade he was headed to the Ivy League. Pencils up in 20 minutes.

The boy exhaled. Before opening the car door, he recalled recently, he twisted open a capsule of orange powder and arranged it in a neat line on the armrest. He leaned over, closed one nostril and snorted it.

Throughout the parking lot, he said, eight of his friends did the same thing.

The drug was not cocaine or heroin, but Adderall, an amphetamine prescribed for attention deficit hyperactivity disorder that the boy said he and his friends routinely shared to study late into the night, focus during tests and ultimately get the grades worthy of their prestigious high school in an affluent suburb of New York City. The drug did more than just jolt them awake for the 8 a.m. SAT; it gave them a tunnel focus tailor-made for the marathon of tests long known to make or break college applications.

“Everyone in school either has a prescription or has a friend who does,” the boy said.

At high schools across the United States, pressure over grades and competition for college admissions are encouraging students to abuse prescription stimulants, according to interviews with students, parents and doctors. Pills that have been a staple in some college and graduate school circles are going from rare to routine in many academically competitive high schools, where teenagers say they get them from friends, buy them from student dealers or fake symptoms to their parents and doctors to get prescriptions.