Young Americans entering adulthood have lived through recession and double-digit inflation, but they are surprisingly cheerful about their economic status and the future of their children, according to a Washington Post-ABC News poll.

Eight of 10 respondents age 18 to 25 said they are better off than their parents were at the same age, and that they expect their children to be better off than they are.

This self-confidence -- the "morning-in-America" mood that these new voters seemed to endorse when they turned out in large numbers for President Reagan in the 1984 election -- was reflected in interviews this month with young people working and studying across the country. Even those who were unemployed held themselves responsible and expressed confidence that they could find work more profitable than making fast-food hamburgers.

Although many economists say this new generation, at the tail end of the Baby Boom, could face a job market glutted with their older brothers and sisters, most of those interviewed seem geared for success and sure that they can achieve it.

As Shelley White, 22, a hotel administration major in Michigan, put it: "There are always new opportunities out there. I don't know what the world will be like in 10 years, but I think it will be for the better."

Optimistic, ambitious, independent, sober, competitive, pragmatic, restless but not rebellious -- this is the portrait that emerges from survey data of young people today. They may lack the tribal identity of '60s youth -- the children who made a thundering impact as the Spock-generation that became the Woodstock and Vietnam generation -- but today's young adults seem to know where they are going. "You can have it all," the beer commercials tell them -- and they appear to believe it.

In their optimism during prosperity, they are little different from the rest of the population. Eight of 10 Americans over 25 say that they are better off than their parents. Seven of 10 say their children will be better off than they are.

As a 1984 report by the National Association of Secondary School Principals on "The Mood of American Youth" concluded: "What was once called the 'generation gap' narrowed to a mere 'crack' during the '70s, and today appears more like a simple hairline scratch. . . . Most students now report that not only do they generally get along with their parents, they also respect and share their parents' values."

In some ways, today's young adults differ profoundly from those of 10 and 20 years ago. The most striking statistics come from the annual college freshmen survey of the American Council on Education at the University of California at Los Angeles.

In 1967, 83 percent of students listed "developing a meaningful philosophy of life" as an essential or very important goal. Only 43 percent say that now. In 1967, 43 percent listed "being very well off financially" as an essential or very important goal. That figure has soared to 71 percent.

The council's survey, based on the answers of 275,000 students at 550 institutions, also suggests a growing selfishness -- something many of the young people acknowledged in the interviews. Ten years ago, 30 percent said that they considered participating in community action essential or very important. Today, the proportion is 23 percent.

Nonetheless, there is a can-do attitude about social change, consistent with the general spirit of optimism. A decade ago, in the aftermath of Vietnam and Watergate, 48 percent of freshmen agreed with the statement, "One can do little to change society." Today, 37 percent share that view.

Similarly, young adults today are more upbeat than their elders about the status of blacks. The Post-ABC News poll found that a clear majority, 55 percent of 18- to 25-year-olds, disagreed with the statement, "black people in the United States are still a long way from having the same chance in life that white people have." Among respondents over 40, 53 percent agreed.

The serious, somewhat driven nature of today's young adults has led to comparisons with the straight-laced youth of the 1950s. But James Ogilvie, who studies changing values at SRI International, a research firm in Menlo Park Calif., points out: "While there's a buckling down and a seriousness about earning a buck as there was in the 1950s, today there's a greater entrepreneurial spirit. Ask people in business school whether they want to work in a big corporation. In the '50s they said yes. Today, they want to be in business for themselves."

As the Republican Party under President Reagan has sought to identify itself with the entrepreneurial and pragmatic values of the 1980s, its popularity among young adults has grown. Washington Post-ABC News polls over the past year show that the younger the voter, the more likely he or she is to identify with the Grand Old Party and approve of the way Reagan handles his job.

Thirty-five percent of 18- to 25-year-olds called themselves Republicans, compared with 26 percent of 26- to 35-year-olds. Among the younger group, 36 percent identified themselves as independents and 23 percent as Democrats.

But many researchers say the pro-business, pro-Republican attitudes do not mean today's young adults are overwhelmingly conservative. The American Council's survey found that "the direction has not been from liberal to conservative, but from left to center." Since 1966, the number of freshmen identifying themselves as "liberal" has dropped, and the number calling themselves "middle-of-the-road" has surged.

On social issues, young people in the '80s share the liberal attitudes of their counterparts in the late '60s and '70s. The Post-ABC News poll shows that they differ sharply from the over-40 group in their attitudes toward drugs, premarital sex and women's roles in the home and work force.

The new generation, said Philip Bowers, a 20-year-old psychology major from Far Hills, N.J., is "not depending on men to marry and bring home the dinner. There's no doubt my wife will have a job. I don't think too many men these days are looking for a wife who will sit around the house."

"When we look closely at attitudes and values on certain political and social issues, we find that today's students are more liberal than they have ever been," wrote Professors Alexander W. Astin and Kenneth C. Green in a paper on the freshmen surveys.

In the 1985 freshmen survey, support for busing as a means toward racial integration in the schools reached an all-time high of 54 percent, up from 37 percent in 1976. Most of the students, 55 percent, said abortion should be legal.

Nearly three-fourths of the students opposed increased defense spending, and two-thirds agreed that "the federal government is not doing enough to promote disarmament." The Post poll asked respondents how serious a threat the Soviet Union is to the United States and found little difference among age groups.

As Fritz Fiedler, a 21-year-old engineering major from Kingston, N.Y., put it: "Eventually, both countries are so scared of nuclear war that we're going to have to come to an agreement. I don't think the Soviets are out to get us. I don't view them as a threat. I don't think we are threatening their system. But I don't think our governments have realized that yet."

Although more young people think that the United States is stronger militarily since Reagan took office, more are apprehensive about war. Post-ABC News surveys last year found that 31 percent of those under 36 thought nuclear war was very likely or somewhat likely in the next few years, compared to 26 percent of those over 36.

But despite this concern, today's young people seem determined to forge ahead.

"We're really focusing on success," said Amy Brezino, a 19-year-old freshman at the University of New Hampshire. "We're trying to fit that image."