A look at the world's under-reported millions; Villages, by Richard Critchfield. Garden City, New York: Anchor Press/Doubleday. $17.95.

During the long wastes of the Vietnam war, one of America's greatest newspapers determined upon a new approach to its coverage. Correspondents, decreed head office, were to get out of the cities. They were to spend long and reflective periods in the Vietnamese countryside. They were to forget the slambang superficialities of Saigon and report to the readers what was really going on in the villages.

It was a worthy effort, but predictably short-lived. For inevitably when the first new crisis in the capital erupted (a coup attempt, a riot, a Buddhist protest -- I forget now which) the editors who had so recently dispatched their men to the countryside were enraged to find so little Saigon manpower available to cope with the crisis dominating the TV screens in their offices back in the United States. So poor Fotheringill (or whatever the hapless correspondent's name happened to be) was hauled back from the rice paddies to play catch-up on the slam-bang story from Saigon.

It is a continuing problem in the news business. Good editors say they want depth and insight from their correspondents. But the competition pressures often divert reporters to the fleeting, but dramatic.

This is especially so in the case of television. In far-flung lands, American TV cameras are trained on the burning monk, the mob at the gates of the military base, the frenzied hordes besieging the embassy compound. Often these events are staged exclusively for the cameras. Yet sometimes life only a few hundred yards out of camera range bears no relationship to the media event being so skillfully staged.

Richard Critchfield is a writer who has sought to redress this imbalance. He was an exhaustive correspondent in Vietnam for the Washington Star. In the years since his writings about village life in the third world, including much in The Christian Science Monitor, have been a beacon of enlightenment to those who would understand this essential strata of society.

Mr. Critchfield has spent long months at a time in villages in Java and Egypt and Mexico and Bangladesh, among other lands. He lives with the people, works with them, talks with them and keeps copious records of their words, their concerns, their hopes.

Village life can be earthy, and there is sometimes graphic description of the drunkenness and drug addiction through which some of the most desperate try to shut out the world.

But the hope that Mr. Critchfield sees is that the world -- particularly the world of Western, and especially American, technology -- cannot be shut out. His story is of remarkably increased production from the new miracle wheat and rice grains developed by Western scientists. Much has been done. He believes much more can be done.

Can the "green revolution" be matched in the most needy of countries by a controlled birthrate? Mr. Critchfield believes that the women of the villages will ultimately decide that.

For Americans, one of his most encouraging findings is the curious love affair villagers across the world have with the United States. "America," he says, "is becoming everybody's second country." Not America as "an imperial political power." But America as a symbol of the good life, vitality, freedom, fun. And American pop culture, starting to penetrate to the villages of the third world in recent years, is credited by Mr. Critchfield as being the catalyst.

For Mr. Critchfield, village life is the key to the third world's future. There will be those who debate him, for a few generals with a couple of hundred tanks can still wreak havoc in the capitals. And newspapers and television networks will still rush to cover those events.

But he has written a most important volume about the world's critical, and badly underr eported, millions.