A friend recently said his 20-year-old son had begun to doubt he would achieve the economic success of his father. "I think the American dream is starting to run in reverse," the son said.

He may be right. The economic landscape is shifting, and there are more than a few signs that this young man's generation - at various economic levels, not just the poorest - could be the first in this country to end up worse off than its parents.Young families have always struggled when starting out.

But many of today's young parents have to struggle harder, and they are falling further behind even as older and more established families hold their ground at a time of more general prosperity.

A recent report of the Children's Defense Fund and Northeastern University's Center for Labor Market Studies documents the economic decline facing families headed by persons under age 30:

- The median income of young families with children (adjusted for inflation) fell by 26 percent between 1973 and 1986 - a loss virtually identical to the 27 percent drop in per capita personal income that occurred during the Depression from 1929 to 1933. Nearly three-fourths of this decline took place during the 1980s.

- As a result, poverty among young families with children has almost doubled, jumping from 16 percent in 1973 to 30 percent in 1986. Rising poverty rates have affected all groups of young families - whether white, black, Hispanic, married-couple or single-parent - and occurred in every region of the country. Indeed, the differences between regions have narrowed since 1973.

While the deterioration of the economic status of young families will not be reversed quickly or easily, two immediate steps can by taken by Congress before its adjournment this year to begin to halt the precipitous decline in their incomes and to help young families with children cope with the increasing economic pressures caused by declining earnings:

- Enact the Act for Better Child Care Services, which would bring the federal government into partnership with state and local governments and employers to ensure that children in working families get safe, quality, affordable and accessible child care.

- Increase the federal minimum wage, which has lost one-fourth of its real value to inflation since it was last raised in 1981. Modest legislation pending in both the House and Senate would increase the minimum wage gradually from its current $3.35 per hour to $4.55 per hour by 1991, thereby recapturing most of the ground lost to inflation during the 1980s.

Beyond these two immediate steps, the nation must adopt a long-term investment strategy beginning in 1989 to respond to the economic disaster confronting young families.

To begin, we must build upon the successes of proven, cost-effective programs such as Head Start, federal compensatory education programs and the Job Corps so that they reach more of the children who need such assistance. These efforts should be coupled with comprehensive strategies to prevent teen pregnancy by building strong basic skills and self-esteem in the early years and positive life options for all teens.