Stopping for a moment on this 106th Labor Day, let's assess the impact of the Reagan administration upon the U.S. labor movement, at one time the closest to a revolutionary movement the United States had known.

While experts differ on President Reagan's impact, one thing for sure is that the past six years have been a challenge to labor's mettle and agenda.

Almost immediately after taking office, Reagan struck the first blow and set an antagonistic tone when he fired 11,400 air traffic controllers who went on strike in defiance of federal law.

That move coincided with a corporate push for a union-free environment, in which union opponents argued that labor had contributed to the high cost of living and inflation. The administration aided and abetted this effort by attempting to retrench on labor laws and safety and health protection.

Meanwhile, as the Reagan administration poured huge sums into defense and serviced corporate America, labor lost ground, unable for myriad reasons to respond as a protector of workers and consumers.

Management continued to have the upper hand, and unions were not able to respond in kind.

Workers in many cases were left stranded because of mergers, foreign competition and an inability of unions to respond quickly to the changes that were occurring.

By standing fast, labor unions did manage to stop some of the retrenchment attempts on labor laws, safety and health protections, and some of the negative consequences of corporate action.

Most labor leaders agree that relations between labor and government changed for the better when William Brock became secretary of labor in 1985.

The following year, when Democrats won control of the Senate, some labor activists were able to move from merely a holding action to take the offensive on such issues as improved child care and parental leave.

Then just three months ago, air traffic controllers hired to replace those who were fired voted overwhelmingly to organize a union, a vote that was hailed by many labor leaders as a sign of rejuvenation for the movement.

Despite this move, some leaders say that labor remains in a state of decline under Reagan. An aide to AFL-CIO President Lane Kirkland pointed out that just as the need for a union became "abundantly clear" to the new air traffic controllers, other workers were beginning to see that strength lies in union participation.

To William Lucy, secretary-treasurer of the American Federation of State, County and Municipal Employees, the largest AFL-CIO public sector union, the air controllers represent an isolated triumph. Lucy, also president of the Coalition of Black Trade Unionists, feels that labor is in decline.

"Although Reagan policies have created greater solidarity among affiliates of the American labor movement, a positive sign, the antilabor attitude has really been put out there and has taken hold so the power of mangement has been brought to bear against unions and workers," he said.

Lucy said he feels that unions are losing the battle against corporate utilizaton of cheap labor in other countries. "I don't think the issue is 'buy America'; the issue is 'invest in Americans,' " he said.

For its part, the administration discounts much of labor's gloom and doom over today's workers.

"The people who put the gloomier cast on it are just wrong," says a spokesman for Labor Secretary Brock. "We've added over 14 million jobs to the economy, and over 12 million are coming in at the higher end of the wage scale.

"The cliche has it that these new jobs are dead-end, minimum-wage fast food jobs, but they're just plain wrong."

Despite the optimism, the reality is that there is little reason for cheering on this Labor Day. Women have yet to achieve parity with men. Blacks are still significantly unemployed -- 12.4 compared with 6 percent for the rest of the population; Hispanics are at 8 percent.

Those rates must be rejected as unacceptably high by the administration, corporate America and unions if the news next Labor Day is to be any better than today.