Much more time will have to pass before a solid, enduring judgment can be passed on the summit meeting that President Reagan and Soviet leader Gorbachev completed Wednesday.

But it's not too soon to conclude that the Moscow summit laid the groundwork for what could become the biggest reduction in East-West tensions in more than four decades.The U.S. and Russia did more at the summit than just sign new arms control agreements requiring advance notification of launching of ballistic missiles and providing for experiments to improve ways to monitor limits on nuclear testing.

The superpowers also approved seven other agreements, including accords to increase the number of high school exchange students over the next two years, expand cultural exchanges, and provide for some limited cooperation in space exploration.

These agreements, however, do not constitute the full measure of the summit's significance.

For one thing, it's certainly important that President Reagan's meetings in Moscow with dissidents and his repeated pronouncements on the need to improve basic freedoms in Russia did not prompt Gorbachev to take a harder line on arms control.

For another, the press conference that Gorbachev held at the end of the summit was the first ever conducted by a top Kremlin leader on his own soil. The challenge now is to build upon this precedent by continuing to make Kremlin leaders more accessible to the public via the press.

Despite the steady but undramatic progress at the Moscow summit, it's still too soon to declare an end to the cold war. The great majority of the 40,000 nuclear warheads the two superpowers have aimed at each other remain in place. Though talks at lower levels are continuing, the two sides remain far apart on how to slash in half their long-range nuclear arsenals and negotiate reductions in conventional armies.

Moreover, though Gorbachev kept angling at the summit for more Soviet trade with the U.S., the prospects remain slim. And they should stay that way as long as Russia relies so heavily on slave labor, retains a government-run economy that prevents it from being very productive, and remains so aggressive. At this point, broader trade would simply make it easier for Moscow to avoid domestic reforms and continue expansionist foreign policies. A change in U.S. trade with Russia should hinge on a change in Moscow's behavior.

Meanwhile, one fact of international political life remains paramount: If Gorbachev seriously expects to improve the lot of the Russian people economically and politically, he simply must reduce the heavy military burden they have long been carrying.

As long as that's the case, there's hope for building on the progress achieved at this week's U.S.-Soviet summit.