The Montgomery County Board of Education voted yesterday to require students to earn better grades to be eligible for extracurricular clubs or team sports under a policy that will be one of the toughest of its kind in the Washington area.

The new eligibility rule, approved on a 5 to 3 vote, will require middle school and high school students to maintain a C average and fail no more than one course during a marking period.

The standards, which are scheduled to take effect next fall, are significantly more stringent than Montgomery's longtime policy, under which students are ruled ineligible for sports and clubs if they fail a course. The current policy does not include a minimum grade average requirement.

The stiffer criteria reflect an effort by the school system to put more of a premium on good grades, but they were questioned by members of student organizations and minority groups, who argued the new policy could affect their students disproportionately.

"The point of raising standards is {that} there is nationally and locally a sense {that} it is important for us to reinforce the importance of academic achievement," said board member Blair Ewing, who was the most outspoken advocate of the new policy during an hour-long debate before yesterday's vote.

"If you are not performing well enough to meet that standard, you ought not be doing other things that take up your time," he said.

But Robert E. Shoenberg, the board's president, opposed the change, calling it "a solution in search of a problem."

"I mainly see it as trying to establish the fact Montgomery County is academically tough," Shoenberg said. "But its effect on improving student grades is likely to be marginal."

He said the higher standard was potentially harmful because it would penalize students who lack the ability to meet the standards, no matter how hard they try. "Lacking the incentive of an extracurricular activity in which they excel as a reason to stay in school, they are likely to turn off, or drop out."

"I'm worried about alienating kids," agreed David Chang, the board's student member. Chang also cautioned that the policy could injure extracurriclar clubs and teams.

He contended that students were not being given enough time to meet the higher standards.

In an effort to blunt the effect on low-achieving students, the board accompanied the policy with a commitment to provide more tutors and other special help for students who cannot meet the new standards.

Board members said they did not have estimates of how many students were likely to be excluded under the new standards.

Montgomery's new policy is similar to one that sparked a protracted controversy before it was approved last year in Howard County. In the District, Prince George's County and Alexandria, students must earn a C average, but there is no limit on the number of courses they can fail.

In Anne Arundel, students must maintain a D-plus average with no more than one failing grade. Prince William requires students to pass five classes each marking period, and to earn at least a C in two of them. Arlington requires students to take at least five courses that count toward graduation, and pass all of them. Staff writers Lisa Leff and Pierre Thomas contributed to this report.