The conservative majority on the Montgomery County school board, whose rule had become increasingly controversial over the past four years, was toppled last night by a slate of four liberals who banded together to oust two board conservatives.

With all 202 precincts reporting, candidates backed by a bipartisan political action committee known as EDPAC led a field of eight, including the two board conservatives, Carol F. Wallace and Joseph Barse, and a slate of two self-styled moderates. The EDPAC candidates had waged a well-financed, efficiently organized campaign highly critical of the current board's policies and attitudes.

EDPAC victors included Marilyn J. Praisner, who led the slate, followed by Odessa M. Shannon, James E. Cronin and Robert E. Shoenberg. Barse was trailing the field. In fifth place was moderate Timothy O'Shea, followed by Wallace and moderate Barry Klein, who was running in seventh place.

The conservatives, frought with internal fighting and stung by a series of highly controversial school closings, needed to retain both seats to maintain the control they gained in 1978.

The EDPAC sweep was hailed by the winners as a resounding victory and a new era in board relations, especially for liberal activists and minorities who repeatedly charged that the board was insensitive to minorities and racial balance.

"We were afraid to expect this kind of victory," said EDPAC candidate Cronin, a professor of history at Montgomery College. "But this is a message to at least some of the voters that the devisiveness of the past is over . . . ."

"The people of Montgomery County obviously care more about their kids than fear," Cronin said. One of the main EDPAC campaign themes was the charge that the actions of the current board, including a number of school closings, were creating an atmosphere where parents of white children were worrying more about forced busing than integrated education.

Barse could not be reached for comment, but Wallace said she did not know what sort of philosophical shift the election portended.

"I wish them the best of luck and I pray they keep the children in the forefront of anything they do," she said.

The victory by the EDPAC candidates, who grounded their support in broad-based organizing, signals a radical shift in command for the board that has been led by Marian Greenblatt since the slate backed by her swept the election in 1978. Greenblatt, who made an unsuccessful bid for the Republican nomination for Congress, orchestrated most of the changes that occurred in the four-year tenure of the conservatives, including instituting a move toward back-to-basics education, ousting a liberal superintendent and attempting to end some voluntary integration efforts.

It was this last effort, coupled with what Greenblatt's critics called an overbearing style, that led to the one-time George McGovern worker becoming the focal point of a campaign that became highly partisan and was bitterly divided along conservative-liberal lines.

When asked what EDPAC's main objective in forming was, the then spokesman said, "We are running against Marian Greenblatt and her policies."

Now only two members of the six-member conservative majority, Greenblatt and Suzanne Peyser, remain.

Board president Eleanor Zappone announced earlier this year she would not seek reelection and Richard Claypoole said he would not run when he was appointed to fill a vacancy last summer.

Instead board member Blair Ewing, the lone dissenter on the board and Greenblatt's most vitriolic critic, appears likely to gain control. Ewing was one of the founding members of EDPAC.

Last night Ewing, speaking from the festive EDPAC headquarters where beer and champagne were flowing, said the victory was "all about decency, civility and due process." Ewing added that contrary to conservative claims, the new EDPAC-dominated board would not lead the 92,000-student school system down the path of permissive education that the conservatives claimed was responsible for their overwhelming victories during the last four years. Ewing said the quarrel was over style and not substance.

Barse and Wallace fared poorly in the primary, coming in fifth and sixth in a field of 15 in which the four EDPAC candidates swept the top four spots.

The accusations about racial insensitivity peaked last summer when the state board of education, in an unprecendented action, reversed three of the Montgomery board's decisions involving school closing and drawing boundaries in the lower Silver Spring area. The state board found that the local board had violated its own racial guidelines.

The incumbents and their colleagues on the board sought to focus debate on their accomplishments in reinstating more traditional education policies and more structured classrooms in the system but that effort was largely lost when the majority of the 15 original candidates seized on the EDPAC antiboard themes.

Supporters of the board majority launched a counter-campaign during the last three weeks, stressing the unity of Barse and Wallace and attempting to align them with two other, unaligned candidates, Klein and O'Shea. But the unity effort fell apart as Wallace continued to attempt to separate herself from the Greenblatt-led majority. The two incumbents, although philosophically aligned, have clashed repeatedly over the years on issues not involving educational matters. Wallace ran on a slate in 1978 managed by Mickey Greenblatt with Barse and Zappone, but this time around she refused to run with Barse because he was accepting help from Greenblatt. The split and absence of a well-organized campaign structure hurt both Barse and Wallace.