High school students' performance on the SAT college-entrance exam remained mostly unchanged from last year, except for notable gains by Asian-Americans, who continue to outperform all other test takers.

Overall, the average score for the graduating class of 2010 in reading remained at 501; climbed in math to 516 from 515; and dropped in writing to 492 from 493, according to scores released Monday.

The combined overall score of 1509 out of a possible 2400 matched last year's tally, which was the lowest since the writing exam was added to the SAT battery in 2006.

The sole bright spot was the performance of Asian-Americans. They posted a three-point gain in reading, a four-point jump in math, and a six-point gain in writing over their 2009 scores.

The SAT news comes a few weeks after results from the ACT college-entrance exam suggested only one-quarter of U.S. high school students possess the academic skills necessary to pass entry-level college courses. Together, the scores underscore the challenge faced by the Obama administration in its effort to boost college graduation rates.

"This report confirms that there are no tricks and no shortcuts to college readiness," said Gaston Caperton, president of the College Board, the nonprofit organization that administers the test. "As America moves out of this recession, we have to fuel the real engine of economic growth, and that is education."

SAT scores are closely watched because the standardized test measures the achievement of students who hope to attend America's top colleges. More than 1.5 million students from this year's graduating class took the exam. Each subject is scored on a scale of 200 to 800 points.

About 42% of test takers were minorities, the highest nonwhite percentage ever to sit for the exam. Non-Asian minorities continued to perform far below white students. African-Americans, for example, posted an average reading score of 429, compared with 528 for whites.

"With persistent achievement gaps between ethnic groups still dangerously separating America's kids, we must redouble our efforts to reform an education system that continues to spend more only to receive less in return," said Jeanne Allen, president of the Center for Education Reform, a Washington D.C., nonprofit that advocates for changes in public K-12 education.

The SAT results suggested that students who took a core curriculum in high school—defined as four years of English and three of math, science and history—scored, on average, 151 points higher than those who didn't take the curriculum.

College Board officials attributed the surge in Asian-American scores—up 20 points in reading and 26 in math since 2000—to the students' choice of courses. More than two-thirds took at least four years of science in high school, versus 59% of all test-takers, and 48% of the Asian-Americans took calculus, versus only 28% of the rest of the pool.

"Our data shows that the American Dream is alive," said Laurence Bunin, a senior vice president at the College Board. "If you apply yourself, take hard courses and do well, you will be ready for college."

Write to Stephanie Banchero at Stephanie.Banchero@wsj.com