It is, says Eleanor Holmes Norton, "the single most important problem confronting the black community today."

Norton gained prominence as an executive aide to the mayor of New York before becoming chair of the U.S. Equal Employment Opportunity Commission under President Carter. But the problem she is speaking of is not the urban crisis, or joblessness, or even racism. It is, in the words of the old rock song, "babies making babies."

More than half of all black children born in America today are born out of wedlock, most of them to teen-age mothers. It is, says Holmes, not merely a problem for the young mothers and their families. It is "disastrous" for the entire black community.

"Ordinarily, young people are expected to provide the group with a fresh start. But what kind of fresh start can there be for us when half the next generation will consist of children who were raised by children? These youngsters, who should be our hope for the future, are virtually guaranteed to grow up with problems of the most severe kind. The implications are disastrous for all of us.

"These children are the ones most likely to have reading and learning difficulties. They are the ones most likely to become truants and delinquents. They are the ones most likely to be untrained and jobless, to be engaged in violent crime. And yet we are scarcely paying attention to the problem.

"It's so much easier to talk about our social problems in terms of young adults who are unskilled and out of work, or into drugs or crime, and so on. But we have not taken note of the fact that the problems begin much earlier-- with children born to mothers who are themselves children."

Norton is aware that the increase in out-of- wedlock births has occurred among whites as well as blacks. But the statistics are far more serious among blacks. Between 1970 and 1979, for instance, out-of-wedlock births among whites increased from 5.7 percent to 9.4 percent. For blacks, the increase was from 38 percent to 55 percent, according to the Census Bureau, and appears to be still climbing.

"The situation would not be nearly as devastating if the extended family had survived the ghetto," says Norton. "It didn't. The sheltered situation that used to exist in black America, even for children of unmarried parents, doesn't exist in the big cities.

"As a result, we have been dealing with symptoms, rather than the basic problems. The schools, which have come under so much criticism in recent years, are expected to deal with a child that has been raised by a child, by a mother who has no parenting skills and who herself may have had inadequate parenting. Child-rearing is difficult enough for a mature adult. These young mothers haven't learned most of what they need to know about themselves, let alone about what it takes to be a competent mother."

Interestingly enough, most of us have been at least dimly aware of the things Norton is talking about. But we have not made the connection between child-mothers and the array of problems confronting black America. The tendency is to see the problems as almost solely the result of racism.

Norton, now a senior fellow at the Urban Institute here, is well aware of the crippling effect of racism. But it doesn't explain everything. It seems reasonable to suppose, as she does, that at least a part of the explanation lies in the dismal numbers from the Census Bureau.

She does see a glimmer of hope. "The evidence is that the old stereotype of unmarried women having large numbers of children, all of them on welfare, seems to be fading. These girls don't necessarily go on to have many children. After the first baby, they clearly seem to be deciding that they don't want a lot more.

"That suggests that it would be more cost-effective, not to mention more humane, to find ways of intervening after the first baby to help the young mother make more reasonable life decisions."

Such intervention might include increased efforts to get these young mothers back in school, or in some sort of vocational training. But she also thinks it is important to provide some structure for their often chaotic lives.

"It could be extremely useful if we could hook these girls up with older, more stable women who could not only help with babysitting and child-rearing instruction but also give some structure to their lives," she suggests. "Even if it was necessary to pay these women, it would be cheaper than a lifetime of welfare."

Clearly something has to be done. As Norton notes, teen-age mothers are becoming the majority of black mothers. If they are having most of the children, they can't help but pass on the problems. That is not exactly a recipe for racial progress.