(MONEY Magazine) – Two months ago, Bill and Vicki Kirchner of Omaha packed off their daughter Casey, 18, for her freshman year at Purdue University in West Lafayette, Ind.Unlike many parents, however, the Kirchners know that the $55,000 or so they're spending for Casey's degree will equip her for something more than a minimum-wage job at a java bar four years from now. Since the eighth grade, their daughter has wanted to become an astronaut in the NASA space program. Even if that dream doesn't pan out, the major she's chosen, aerospace engineering, is still likely to launch her toward a hefty paycheck. Women with bachelor's degrees in engineering pull down a median annual salary of $49,070, according to the Bureau of Labor Statistics. That's more than women majoring in any other subject except economics.

You may be wondering if the $2,100-a-year average tuition for in-state students at a public college or the $12,400 tariff at a private school will prove to be as good an investment for your teen--especially if the kid is clueless about which major he or she should choose. You're not alone. "Given the level of economic anxiety today, a lot of parents are concerned about which career their kids should pursue," says Steven R. Antonoff, an independent educational consultant in Denver.

That concern is understandable. But there's no rush for your high school junior or senior to select a major. Most colleges don't require students to choose a field of study until the start of their third year. In the meantime, however, it's a good idea to prepare your child to make an informed choice. Start by having him or her trek down to the public library and take a look at the Occupational Outlook Handbook, which shows what college graduates in different jobs typically earn. Your daughter with the champagne taste and a desire to go into social work will be better off knowing now that social workers rarely tool around in new BMWs. Then encourage your high schooler to do some research on the careers that various fields of study generally lead to. That way the kid will be prepared for both the good (intellectual challenges) and the bad (60-hour workweeks) that go along with succeeding at that first job.

Before your child commits to a major, here are some of the important points you should discuss together:

--What you learn affects how much you earn. No major comes with a guaranteed ticket to the good life, but the odds of snagging a well-paying job are considerably higher in some fields of study than others. That's the conclusion of a BLS study released last December based on a National Science Foundation survey of 215,000 men and women who hold bachelor of arts and sciences degrees and are not self-employed. (For a look at the majors with the biggest and smallest earnings, see the table above.) The study revealed, for example, that 29% of men who majored in engineering rank among the top fifth of all male wage earners, while only 9% fall into the bottom fifth. By contrast, only 4% of men who majored in social work made it into the top 20%, while 43% ended up at the bottom of the heap.

--Don't automatically assume a liberal arts degree relegates you to a subpar salary. Pre-professional or business majors are not necessarily the surest route to big bucks. The BLS study showed that men who majored in liberal arts subjects such as political science and government (median annual income: $41,022) or psychology ($40,716) generally earn more than those who got their degrees in social work ($32,171) or education ($34,470). Similarly, women who majored in liberal arts and general studies (median income: $32,074) outearned those who studied education ($27,988) or home economics ($28,275). One reason: The training that students receive in certain liberal arts subjects, such as psychology, prepares them for high-paying fields like sales and marketing.

Conversely, a B.S. in business hardly assures you of a fat paycheck, with a rising supply of M.B.A.s soaking up the best-paying corporate jobs. Indeed, men who majored in business are almost as likely to be at the bottom of the pay scale as at the top.

--Math-intensive majors usually lead to higher pay. Surprise, surprise. High-paying fields of study usually require lots of math courses. So children who ace calculus can probably settle on fields that are rewarding and lucrative. That doesn't necessarily mean that kids who can't add two columns of numbers without a calculator are doomed to a life of penury. Even low-paying fields have at least some jobs that command big bucks. Example: Though men who majored in visual and performing arts earn a median income of just $32,972, 12% of these grads pull down more than $62,400 a year--enough to catapult them into the top 20% of all male earners.

Once your child has realistic salary expectations, it's time to explore a few fields. "Many young people choose a major based on vague images of a lifestyle they want to attain," says Arthur W. Chickering, a former professor of education at George Mason University and co-author of How to Get the Most out of College (Allyn & Bacon, $15.95). "They want to be a doctor because doctors make lots of money, but they know zip about what the job really involves."

So have the kid write to trade and professional associations for information about careers. Cull the names and addresses of outfits worth getting in touch with from the Encyclopedia of Associations at your local public library. To give your child a firsthand look at typical workdays in various occupations, ask relatives, friends and business associates if the kid can shadow them for a day or two on the job. Once your teen starts college, he or she may be able to get hands-on work experience by landing internships in specific fields.

When your child eventually chooses a major that leads to a fulfilling career--even if it's not a top-paying one--both of you will earn a tremendous return on your huge financial investment in his or her degree. And obviously there's more to a college education than vocational training. Says wise-beyond-her-years Casey Kirchner: "If you find something to do that really interests and excites you, you'll be excited about life."