Fifteen years ago, the gender gap was an issue that filled the headlines: By high school, girls were falling 50 points behind boys on the math section of the SAT, the leading college-entrance exam.
But a new study, published in this week's edition of the journal Science, shows the gap has disappeared. Researchers looked at standardized test scores of more than 7 million students, ranging from the second grade to high school junior. Whatever gender differences there once existed between girls and boys in terms of math performance are gone.
"The differences are now trivial," said Janet Hyde, a professor of psychology and women's studies at the University of Wisconsin, who led the research.
Most parents -- and even girls themselves -- accepted the stereotype that girls were simply not hardwired to excel in mathematics.
"Every time I see math, I just, I try and stay away from it," said one teenage girl, interviewed by ABC News in 1994.
"You don't get it, and you feel like you're the only one that doesn't get it," said another.
But that was then.
"The fact is that I understand it," says Romona Twiddle, a 14-year-old who is part of a special girls-only program at the New Jersey Institute of Technology this summer in Newark. "It just comes natural to me."
Romona and three classmates are building a robot together. A few buildings away, younger girls are playing "Environmental Science Jeopardy" with their teacher.
Teachers have reached out aggressively to girls, urging them to get involved in science projects and to take math classes.
Among other things, high tech has turned cool. Students text and download at new highs, and geeky role models show students that math is the gateway to a future in technology.
"Being interested in science, engineering and technology does not make you a geek, and as a matter of fact it's the geeks who rule the world," said Suzanne Berliner Hayman, who heads the summer program at the New Jersey Institute of Technology.
The message seems to be working, say researchers. For the first time, girls are taking math as often as boys.
"We are not born knowing how to do calculus," said Hyde, the University of Wisconsin professor. "When girls take classes at the same rate as boys, we tend to get a narrowing of the gender gap."
That program in New Jersey happens to be girls only, which makes things easier for them.
"Boys are always very competitive, and they want to prove that they're better," said 15-year-old Kate Goodman, a classmate of Romona's at the New Jersey Institute of Technology. "Boys like to fool around a lot too."
While most of America's engineers are still men, that demographic is also shifting. Half of the students who continue on to get math degrees are now female.