The coming shortage of teachers, unlike the last one, will not be caused primarily by booming enrollments. The numbers of children are currently rising, but not dramatically. The chief reason for the shortage ahead is the number of teachers who will retire in the late 1980s. A generation of people who entered the profession after World War II will shortly be leaving it. A great deal depends on the quality of the young teachers who take their places.

During the 1960s, when school systems were struggling desperately to find teachers, there was a perceptible erosion in the standards of hiring. That usually happens in a field expanding rapidly with inadequate preparation. This time everybody -- school boards, state legislatures, universities -- has plenty of warning.

There's a lot of debate over the teachers' tests that an increasing number of states require, and it's true that there's no way to measure imagination and flair in a written test. But those tests are indispensable for setting a basic enforceable level of competence. How can states go farther, and attract young teachers who greatly exceed that basic level?

Salaries are crucial, and those systems that offer below-average money cannot expect above-average teaching for their children. But there's more to it than money alone. Recruiting unusually able teachers needs to begin years before those teachers are hired. The Carnegie Foundation for the Advancement of Teaching has suggested, for example, that state universities offer special scholarships for gifted students who plan to teach in the public schools.

Whether young teachers of high potential stay in teaching often depends on the support and encouragement that they get in their first few years. It's time to speed up the experiments that give the best of the experienced teachers a higher rank, formal supervisory responsibilities and commensurately higher salaries. A well-run school in the late 1980s will need a reliable system of transmitting the standards and practices of the best of its senior staff to the new arrivals. That means master teachers, working directly and continually with the recruits.

The public schools are, among other things, the most influential of this country's civil rights programs. If there is to be equality of opportunity, the ingredients will have to be manufactured in the schools. If all children are to go as far as their abilities can carry them, they will need teachers of great skill and energy. People of high ability are not likely to enter teaching in sufficient numbers unless school systems go to work, vigorously and promptly, to recruit them.