(MONEY Magazine) – By thoroughly investigating colleges now, your child can avoid having to switch schools later on. Each year, an astonishing number of students decide that they made the wrong choice. Based on past experience, the National Institute of Independent Colleges and Universities estimates that 18% of the 2.5 million young men and women who enroll in college this fall will not return after their first year. And a startling 44% will drop out before earning a degree. One reason: many students enroll without knowing for sure that the school is right for them. ''Students' expectations of college life are often short on reality,'' says Fred Zuker, vice chancellor at the University of California at Riverside. And no wonder. Colleges are far from candid about themselves in competing for students. In glossy sales brochures and videos as slick as TV commercials, the schools portray themselves as meccas for personal fulfillment and educational achievement. They frequently fudge the facts about key issues like student/faculty ratios, and they make no mention at all of problems such as bigotry, crime, and alcohol and drug abuse. With help from parents, however, college-bound youngsters can do the aggressive digging that will lead them to the right college. One consoling fact to remember: you're not looking for the single perfect school. There are probably a dozen or more that can offer your child an excellent education and a rewarding college experience. The first step -- and perhaps the hardest -- is for the prospective collegian to figure out what he or she really wants in a school. A few of the questions that your son or daughter needs to ponder: Can I navigate the hazards of a large, impersonal state university, or will I do better at a smaller school? Will a small college, particularly one in a rural setting, be too confining? Am I disciplined enough to design my own plan of study, or would I be better off at a school with many required courses? Once you and your child have established a general set of guidelines -- ideally by April of junior year in high school -- you can draw up a roster of 15 to 20 potential choices. For help, call on your high school's college counselor and read guidebooks such as Choosing a College by Thomas Sowell (Harper & Row, $7.95) and Looking Beyond the Ivy League by Loren Pope (Penguin, $7.95). To illustrate the selection process, let's assume that your child wants to consider only small, coed schools within 250 miles of home. The high school counselor can make suggestions and probably give you computer printouts of basic information on each school that meets your criteria. Next, do a reality check. You might, for example, have your child visit one of his picks as well as a school that's very different. ''Students come from a small town and decide that a large university is just what they need,'' says Zuker. ''Then they discover nobody says hi to strangers, there are 700 kids in every class and the inner city is a couple of blocks away.'' During the summer between junior and senior years, you and your child should begin intensively researching the schools on your list. Either by phone or by letter, ask each admissions department to send you its information packet, which normally includes brochures and an application. And be sure to ask for a course catalogue, which will give you more of the lowdown on a school's academic life than the viewbook with its professional photographs will. The catalogue can answer several important questions: How many courses are students expected to take each term? Does the school have many required courses? Do senior professors teach at the freshman and sophomore levels? Is there a good mix of lecture courses and small seminars? Finally, does the curriculum cover a wide range of subjects in depth? It can be a mistake to choose a school simply for its strength in one department. ''The vast majority of freshmen switch majors at least once,'' says John Gardner, director of the National Resources Center for the Freshman Year Experience, an educational policy research project at the University of South Carolina. Be sure to get a clear picture of student living arrangements as well. At many large state institutions, such as the University of California at Berkeley, there isn't nearly enough on-campus housing for freshmen, much less anyone else. And finding a reasonably priced apartment near campus can use up a lot of energy that would be better spent studying and adjusting to college life. For some telling inside information, ask the admissions office for the college's dropout rate and the kinds of reasons students give for leaving. Their comments may point to areas of concern you would not learn about from other sources. Answers to your questions should enable your child to cut his list to six contenders by the beginning of his senior year. Now, start to visit each campus -- and that means more than the guided tour. ''Only a day or two on campus, attending class, eating in the cafeteria, sleeping in the dorm will tell you whether it's a school you can be happy in,'' says Vincent Tinto, a Syracuse University sociologist and author of Leaving College (University of Chicago, $19.95), which examines the reasons freshmen drop out. With or without you, the future freshman should talk to as many students and faculty members as possible. Among the questions to ask: How many years does the average student take to graduate? To what degree do faculty advisers get involved in planning a course of study? How tough are the reading lists and exams? What are the registration procedures, and is it hard to get admitted to popular courses? Will you need to join a fraternity or sorority to have an active social life? Finally, a walk through the library on a weeknight will give your son or daughter a good idea of how seriously the students take their course work. The atmosphere within the residence halls can be just as important as academic life, and the best way for a prospective student to learn about it is to spend a night or two as a guest of the school -- during the week is preferable, because some schools' dorms empty out on weekends. Many admissions offices will arrange such visits. Whether or not an overnight stay is possible, be sure to find out about co-ed floors and rules on drinking. ''Seemingly minor things can make you very unhappy -- the noise level, the shabbiness, the shortage of resident advisers,'' says Gardner. Worse, some new students discover too late that dorm life is a nonstop party that interferes with studies. You and your child might also chat with the director of student life about crime, alcohol abuse, racial tension and other campus problems. And the staff of the student newspaper can be a good source for alternative opinions about those issues. In addition to specific information, these conversations can help your child gain a sense of campus life. After all, these are the sort of people your child will be living with for four years. ''The biggest reason students change schools or drop out altogether isn't poor grades or lack of money,'' says Marie Friedemann, a private educational counselor in Denver. ''It's that they just don't feel connected.'' Her message to parents: help your son or daughter get plugged in well before the first day of classes.