On a September night six years ago the Montgomery County Board of Education approved a controversial resolution setting up a program of voluntary school integration. The measure, invoking high-minded sentiments and the "ideals of a democratic society," was a crowning moment for the board's liberal majority who saw their new policy on racial integration as part of Montgomery County's celebrated progressive legacy.

"We believe in the inclusive society, and we intend to do something about that," said Roscoe Nix, the only black member of the board then. "I am proud of the fact that we are not attempting to appeal to that which is fearful but to appeal to that which is good."

Last week that same policy was amended by the action of a different breed of school board, a board that, while only six years removed from its predecessor, reflects a new majority, a radically altered political climate and a new set of assumptions about schools. Seemingly minor as the amendment was, many Montgomery liberals, PTA groups and minorities viewed the new policy as a setback in the crusade for a pluralistic society, and a symbol of a new attitude which Roscoe Nix, six years later, brands as "proud and open racism."

The action the school board took last Tuesday will curtail efforts to remedy the high enrollment of minorities in schools in the southeastern part of Montgomery by altering the definition of when a minority population is disproportionate. The revised policy is only one facet of a complex plan which, when completed this fall, will guide the largest school closing effort in the county's history. Until then the effects of the board's action cannot be fully measured.

But it is clear that the school board has embarked on a new approach to minorities in the schools -- one that de-emphasizes integration and one that is likely to be debated and fought over for months to come. Moreover, given the demographic trend of increasing minority growth, especially inside the Beltway, the controversy seems destined only to intensify.

Although the policy change itself made no mention of busing, busing will doubtlessly be reduced as part of the board majority's program to establish "neighborhood schools." Integration is perceived as synonymous with busing, and busing to integrate is roundly condemned in Montgomery, despite the fact that it is not expensive, involving 17 schools and about 2,000 of the county's 98,000 public school children. The average trip is 2.5 miles.

Again, no action has been taken yet, but the board has made clear its intention to scrap the existing cluster system that promotes voluntary integration by using special programs and grade reorganization to bring white students into schools with high minority enrollments and minorities into schools that are predominantly white.

More difficult to answer are other questions raised by the new policy. Will it result in social and racial isolation in the Takoma Park and Silver Spring areas of the county, the erection around down-county schools of what critics call "an educational Berlin wall?" Why did the board act slow on this sensitive issue when political figures in the county -- even board members themselves -- are expressing concern over the rise in racial and other hate incidents in Montgomery? Is the charge of recism fairly applied to the so-called conservative majority that gained control over the school board in 1978 and has so substantially changed its course and tenor as to arouse deep concern in some quarters of this education-conscious county?

"Part of the intensity of feeling comes from the fact that few issues inflame Montgomery residents like schools. The public school system annually produces three times the nation's average in National Merit Finalists, widely judged the cream of the crop in what statistics show is the nation's best educated metropolitan area.

The policy revision adopted Tuesday was roughed out by Marian Greenblatt, leader of the conservative majority and a politically ambitious woman with a PhD in education as well as enough popularity to outpoll Ronald Reagan in the county in the 1980 election.

Since 1975, under its Quality Education/Racial Balance policy, the school board has committed itself to seeking ways to redress the racial imbalance in schools where minority enrollment exceeds 50 percent. Under the revised policy, the board will not look at a school until the minority percentage exceeds 60 percent. For example, at Blair High School in Silver Spring where the minority enrollment is 53 percent, the superintendent, under new board policy, is now no longer obliged to look for means to remedy the racial imbalance.

Most importantly, the percentage that signals the planners is a "floating" figure that rises as the percentage of the minority students in the county increases. As more minorities enter the public school system, schools will be allowed to get higher concentrations of minority students.

Greenblatt defends such a formula as sound policy, saying it will help the school system come to grips with "natural housing patterns" and the dramatic growth of minority enrollment, which has climbed from 11 to 22 percent in the past six years. And it represents a key step toward the board's primary goal of establishing "neighborhood schools." That phrase has long since become a conservative slogan which opponents charge appeals to the fears and prejudices of whites.

The policy change was spurred by the conservative majority's desire to use the closure of 34 schools over the next five years as an opportunity to reconstitute the school system in accord with conservative educational philosophies. Last winter the conservatives told Superintendent Edward Andrews not to consider racial balance as a factor when screening schools for closure.

The board has also directed the superintendent not to create any new schools through consolidation or boundary changes that would have a minority population higher than 20 percent of the countywide figure, a move that would seem to preserve the status quo in schools where whites are now in the majority.

Board president Carol Wallace sees the pattern not as racial hostility but a new emphasis on oldfashioned education. "I remember being castigated three years ago for saying educators should look at all children and see the same shade of purple. We should be looking at children and asking what are his educational needs. That's what we're trying to do now."