Average scores on the reading and math sections of the SAT test declined slightly this year, as the number of high school students taking the standardized exam grew larger and more diverse than ever before, according to a report released this morning by the College Board on the performance of the high school class of 2007.

The average score on the critical reading portion of the SAT, which used to be known as the verbal test, was 502 out of a possible score of 800 — a decline of one point from last year. The average math score declined by 3 points, to 515. The average score on the SAT writing test, which was introduced two years ago, was 494, a drop of 3 points.

It was the second year in a row that the College Board, the nonprofit organization that administers the SAT, reported score drops on the college entrance exam.

The declines for the class of 2007 were not caused by one single factor, the officials said. But the increase in the number of traditionally underrepresented minority and low-income students taking the test played a part, they said. So was a new requirement in Maine that all high school seniors take the exam, including those who would not in the past have viewed themselves as college-bound.

“The larger the population you get that takes the exam, it obviously knocks down the scores,” Gaston Caperton, the president of the College Board, said in a news conference this morning. College Board officials called the decline from 2006 to 2007 statistically insignificant.

In 2006, the first class to take a new three part test including a writing section, average SAT scores showed the largest decline in 31 years: 5 points in critical reading and 2 in math. Together the pattern for the expanded SAT reinforced concerns by many guidance counselors that students were getting tired out by the new three-part test, which runs for three hours and 45 minutes, rather than three hours.

But officials of the College Board attributed the declines last year to a drop in the number of students who took the exam more than once. Experience shows that students’ scores go up when they take the SAT multiple times — typically gaining 14 points a section when they take the test a second time and an additional 10 or 11 points a section on a third try.

Today, the College Board trumpeted the size of the group that took the SAT — nearly 1.5 million seniors — and the expanded diversity of the test-takers. Hispanic, African-American and Asian-American students accounted for 39 percent of the seniors who took the test, with Hispanic students representing the largest and fastest growing minority group to take the exam.

In all, 35 percent of the class taking the SAT would be the first in their family to attend college, mirroring the broad diversification of the college student population that university officials have been noting and encouraging in recent years.

Several officials of the College Board noted that, in some instances, the traditional gaps between minorities and low-income students and the overall population of test takers had narrowed this year. But much of the data released today appeared to bolster the idea that the increased numbers of minority and low-income students taking the SAT had contributed to the decline in scores.

For example, the average score for students who planned to apply for financial aid in college was 501 in critical reading and 508 in math; the average scores for students who did not intend to apply for aid was 530 in critical reading and 548 in math. The average scores for students whose parents did not graduate from high school was 421 in critical reading and 445 in math; the comparable averages for students whose parents are college graduates was 522 and 533.

Similarly, there were racial and ethnic differences. The average scores for black students were 433 in critical reading and 429 in math; the averages for Puerto Rican students was 459 and 454, and the averages for white students were 527 and 534.

The average scores among New York State students in the class of 2007 were 491 in critical reading and 505 in math.