It should be quite evident by now that the United States has a vast literacy problem. In September of this year, the major networks and newspapers took part in a campaign to alert the general public to adult illiteracy--and to urge illiterate adults to seek help.

Much useful information was disseminated. But with it came much confusion and many questions. How many American adults are illiterate? Why the national concern now? Are present efforts likely to succeed?

It is extremely difficult to cite estimates of adult illiteracy--mainly because they come from different surveys and are based on different standards of literacy. Literacy is not an all or none condition. It is a point on a continuum from lower to higher levels of literacy development.

From this continuum one can separate out three groups--a basic literacy group who either cannot read at all or can read only the simplest signs and labels (about 1 million); a group who are often classified as functionally literate; they can read simple materials--but only at an elementary school level (about 25 million); and a group who are able to read elementary level materials, but who cannot cope with the more complex materials of an information high-tech society (about 50 million).

Thus, the largest numbers of adults can read something; the National Assessment of Educational Progress reported this year that 98 percent of young adults (21 to 25) could "read and understand the written or printed word at some level." But very few of these young adults could read at more complex levels. Only 37 percent could read and understand the main argument in a column by Tom Wicker from The New York Times.

Increasingly, a high level of literacy is required for work, for citizenship, for personal needs. Most technical manuals in the military and in industry require a relatively high literacy level (about a 12th grade reading level on a standardized reading test). It is the level sought by adults who lose their jobs in manufacturing and who seek advanced training and high school equivalency diplomas.

Where is the greatest need in adult literacy? It is at all levels--from the completely illiterate to those who seek advanced literacy. The greatest numbers, however, are at the high literacy levels. Indeed, this characterizes the current national literacy thrust.

There have been other thrusts in past years. But the current adult literacy thrust seems to stem from the recognition that, while a little bit of literacy is better than none, it is not good enough today. What is needed today is the ability to read highly complex materials and to use it to solve problems and to learn on one's own. This level of literacy cannot be taught by engaging in a few reading excercises. It requires higher levels of language development, higher levels of reasoning, and advanced reading and study strategies.

Can the adult literacy problem be solved by present efforts? I do not think so. There is too great a dependence on untrained volunteers--volunteers who, according to many of the TV announcements, need only be "caring adults."

This must strike a depressing note in the hearts of elementary and secondary school teachers who, year after year, failed to teach these same students when they were in school. Most of today's adult illiterates were poor readers in elementary or high school. They needed and probably still need specialized, professional help. Is it possible that an untrained volunteer can help them now?

In a recent survey of adult literacy centers in the Boston/Cambridge area, undertaken at the request of Derek Bok and John Shattuck, the directors reported a need for trained teachers, validated testing and diagnostic instruments, tested methods and materials, and long-term funding. The recent literacy campaigns have resulted in large waiting lists--in the hundreds at some centers--with no increases in funding.

Perhaps, the best way to solve the adult literacy problem is by prevention--with better instruction and services for all children, and particularly for those that tend to lag behind. We need to provide help to the millions of children who have special problems in learning to read and who tend to remain behind in reading and related academic subjects during elementary and high school.

This group includes children from low-income families, ethnic minorities, non-English or recent speakers of English, and those with specific reading and learning disabilities (dyslexia). Taken together, they make up about one-third or more of the school population--some tens of millions of children and young people who have the mental ability to make good progress in reading, but who cannot do so without additional help.

When we compare the numbers of children who are having difficulty with the numbers of adults needing assistance with literacy, we find that they are quite similar. Most adult illiterates were children or young people with reading problems. It would be easier and less costly--in human and in financial terms--to help them when they first cried out for the help.

JEANNE S. CHALL is professor of Education, director of the Harvard Reading Laboratory and chairman of the Reading, Language and Learning Disabilities program at the Graduate School of Education. She is an educational psychologist and has written widely on development and the psychology of reading, including "Learning to Read: The Great Debate" and "Stages of Reading Development."