Short of becoming a reality TV star, the answer is rote and, some would argue, rather knee-jerk: Earn a college degree.

The idea that four years of higher education will translate into a better job, higher earnings and a happier life — a refrain sure to be repeated this month at graduation ceremonies across the country — has been pounded into the heads of schoolchildren, parents and educators. But there’s an underside to that conventional wisdom. Perhaps no more than half of those who began a four-year bachelor’s degree program in the fall of 2006 will get that degree within six years, according to the latest projections from the Department of Education. (The figures don’t include transfer students, who aren’t tracked.)

For college students who ranked among the bottom quarter of their high school classes, the numbers are even more stark: 80 percent will probably never get a bachelor’s degree or even a two-year associate’s degree.

That can be a lot of tuition to pay, without a degree to show for it.

A small but influential group of economists and educators is pushing another pathway: for some students, no college at all. It’s time, they say, to develop credible alternatives for students unlikely to be successful pursuing a higher degree, or who may not be ready to do so.

Whether everyone in college needs to be there is not a new question; the subject has been hashed out in books and dissertations for years. But the economic crisis has sharpened that focus, as financially struggling states cut aid to higher education.

Among those calling for such alternatives are the economists Richard K. Vedder of Ohio University and Robert I. Lerman of American University, the political scientist Charles Murray, and James E. Rosenbaum, an education professor at Northwestern. They would steer some students toward intensive, short-term vocational and career training, through expanded high school programs and corporate apprenticeships.

“It is true that we need more nanosurgeons than we did 10 to 15 years ago,” said Professor Vedder, founder of the Center for College Affordability and Productivity, a research nonprofit in Washington. “But the numbers are still relatively small compared to the numbers of nurses’ aides we’re going to need. We will need hundreds of thousands of them over the next decade.”

And much of their training, he added, might be feasible outside the college setting.

College degrees are simply not necessary for many jobs. Of the 30 jobs projected to grow at the fastest rate over the next decade in the United States, only seven typically require a bachelor’s degree, according to the Bureau of Labor Statistics.

Among the top 10 growing job categories, two require college degrees: accounting (a bachelor’s) and postsecondary teachers (a doctorate). But this growth is expected to be dwarfed by the need for registered nurses, home health aides, customer service representatives and store clerks. None of those jobs require a bachelor’s degree.

Professor Vedder likes to ask why 15 percent of mail carriers have bachelor’s degrees, according to a 1999 federal study.

“Some of them could have bought a house for what they spent on their education,” he said.

Professor Lerman, the American University economist, said some high school graduates would be better served by being taught how to behave and communicate in the workplace.

Such skills are ranked among the most desired — even ahead of educational attainment — in many surveys of employers. In one 2008 survey of more than 2,000 businesses in Washington State, employers said entry-level workers appeared to be most deficient in being able to “solve problems and make decisions,” “resolve conflict and negotiate,” “cooperate with others” and “listen actively.”

Yet despite the need, vocational programs, which might teach such skills, have been one casualty in the push for national education standards, which has been focused on preparing students for college.

While some educators propose a radical renovation of the community college system to teach work readiness, Professor Lerman advocates a significant national investment by government and employers in on-the-job apprenticeship training. He spoke with admiration, for example, about a program in the CVS pharmacy chain in which aspiring pharmacists’ assistants work as apprentices in hundreds of stores, with many going on to study to become full-fledged pharmacists themselves.

“The health field is an obvious case where the manpower situation is less than ideal,” he said. “I would try to work with some of the major employers to develop these kinds of programs to yield mastery in jobs that do demand high expertise.”

While no country has a perfect model for such programs, Professor Lerman pointed to a modest study of a German effort done last summer by an intern from that country. She found that of those who passed the Abitur, the exam that allows some Germans to attend college for almost no tuition, 40 percent chose to go into apprenticeships in trades, accounting, sales management, and computers.

“Some of the people coming out of those apprenticeships are in more demand than college graduates,” he said, “because they’ve actually managed things in the workplace.”

Still, by urging that some students be directed away from four-year colleges, academics like Professor Lerman are touching a third rail of the education system. At the very least, they could be accused of lowering expectations for some students. Some critics go further, suggesting that the approach amounts to educational redlining, since many of the students who drop out of college are black or non-white Hispanics.

Peggy Williams, a counselor at a high school in suburban New York City with a student body that is mostly black or Hispanic, understands the argument for erring on the side of pushing more students toward college.

“If we’re telling kids, ‘You can’t cut the mustard, you shouldn’t go to college or university,’ then we’re shortchanging them from experiencing an environment in which they might grow,” she said.

But Ms. Williams said she would be more willing to counsel some students away from the precollege track if her school, Mount Vernon High School, had a better vocational education alternative. Over the last decade, she said, courses in culinary arts, nursing, dentistry and heating and ventilation system repair were eliminated. Perhaps 1 percent of this year’s graduates will complete a concentration in vocational courses, she said, compared with 40 percent a decade ago.

There is another rejoinder to the case against college: People with college and graduate degrees generally earn more than those without them, and face lower risks of unemployment, according to figures from the Bureau of Labor Statistics.

Even those who experience a few years of college earn more money, on average, with less risk of unemployment, than those who merely graduate from high school, said Morton Schapiro, an economist who is the president of Northwestern University.

“You get some return even if you don’t get the sheepskin,” Mr. Shapiro said.

He warned against overlooking the intangible benefits of a college experience — even an incomplete experience — for those who might not apply what they learned directly to their chosen work.

“It’s not just about the economic return,” he said. “Some college, whether you complete it or not, contributes to aesthetic appreciation, better health and better voting behavior.”

Nonetheless, Professor Rosenbaum said, high school counselors and teachers are not doing enough to alert students unlikely to earn a college degree to the perilous road ahead.

“I’m not saying don’t get the B.A,” he said. “I’m saying, let’s get them some intervening credentials, some intervening milestones. Then, if they want to go further in their education, they can.”