THE CENSUS BUREAU provides some good news for female workers this Labor Day. The gap between male and female earnings is closing. Progress is slow, but it is surely steady. In 1979, women who worked full-time earned, on average, only 62 percent of what men earned. Now that figure is 70 percent.

The most encouraging data concern younger women -- those still in their twenties. These women earn 83 percent of what is paid to their male counterparts. This showing is probably due to two factors. One is that younger women are entering traditionally male-dominated fields in record numbers. In the past seven years, for example, the percentage of accountants and auditors who are women rose from 34 to 45, the percentage in the legal profession went from 10 to 15 and the share of computer programmers from 28 to 40. These women are earning a much higher income than their peers who have remained in female-dominated occupations. The second factor is that young women are less likely than in the past to have had interruptions in their careers for child-bearing and child care. Time taken out when children are young invariably sets back earning potential, and many women never catch up to their male colleagues who stayed on the job.

Most experts believe that about half of the wage gap that still exists is due to the family obligations women carry in this society. Many women believe the rewards of family life more than compensate for the loss in earning potential. But there are other women who want to work or who need to work, who suffer because of the high cost or unavailability of good day care. Improvements in this area would be reflected in the female earnings statistics.

After all the factors involving women's family and career conflicts are taken into account, there remains an earnings disparity that can be explained only by discrimination. There are still industries where women are not thought strong enough or fast enough or mechanically minded enough to do the job. There are still parts of the country where a woman in a male-dominated profession is thought to be unnatural or at least unseemly. And there are still individual managers, bosses and coworkers whose attitudes toward women workers are simply hostile. Gradually, though, the ice is melting, ability and achievements are being considered before sex, and women are moving up.