You, your parents, and college acceptance day

April 15 is the day when colleges across the country send out to high school seniors the coveted fat letters of acceptance or the dreaded thin letters of rejection, euphemistically termed ''letters of denial.''

In spite of the fact that about 83 percent of the nation's college applicants will be accepted to a selective public or private college, those who have pinned hopes on one or two particular colleges and who have not received acceptances will take small comfort from this statistic.

Two years ago demographers began predicting that by 1982 college acceptances, even among highly competitive colleges, would be in a buyer's market. But for the moment applications to selective colleges remain very high. Some have shown an increase as high as 18.7 percent over last year. More students are choosing to go to college after high school, and they are pinning high hopes upon a prestigious degree thought to open doors some years down the road.

If you have received an acceptance to a good school on your list (and there should have been no school on your list you didn't respect or like for some reason) but are still feeling disappointed, keep a few points in mind.

While where you go to college is not the most important decision you will ever make, it is an important one that will affect your immediate future and growth. Return to visit the campuses of your top choices, sit in on classes, and follow your heart.

Most of what you get out of college will be up to you anyway. An unmotivated student at the most prestigious college will wilt away.

Decide to pick the school you like best from among those that have accepted you and make the very most of the opportunities there. Don't fall into the trap of devaluating the very schools that have recognized your achievements by an acceptance. Remember the Groucho quip, ''I wouldn't want to belong to any club that would have me as a member.'' You can always make a change after sophomore year providing your marks are high. Sixty percent of students now complete their B.A. at institutions other than where they started.

If you received no acceptances, or only wait lists, don't despair. Try to discover by calling admissions offices and explaining your predicament what part of your application was ineffective. Perhaps your grades were too low to qualify you for any of the schools you selected. Admissions officers can be very helpful in suggesting where there might be available spaces for students who have been closed out of an acceptance. There are some excellent schools that will oftentimes take a second look at applications when this disaster occurs, especially if you can get your counselor to intercede for you.

Some colleges have open deadlines through August or until all the spaces are filled. Don't rule out one of these if you really want to get started on your undergraduate education.

Also, if you can organize a year off into a productive experience, it may not be a bad idea for you to build up some experience and a new way of presenting yourself a year later.

College acceptance day can be parents' finest hour, regardless of the outcome. Surely, if your child is happy you'll share in that happiness and help him celebrate. If, however, you are called on for support, be there to give it. Children learn stress from their parents to a large degree; your ability to cope with stress sets a model. There is no guarantee in life that we will always get what we want. The only recourse is to cope as best we can when we are disappointed.

Lend support to the workable choices your son or daughter has before them. Assure them that this is not a life or death matter. Build them up in the eyes of their peers. Accompany them to the campus where they will be going and try to single out its strengths and opportunities.

Build a positive start. No matter how caught up in a bout for independence your son or daughter may be, there is no room now for ambivalence. They need your support. They need you to convince them that test scores and rejections do not necessarily measure such qualities for success as creativity, patience, leadership, promise, capacity to learn, motivation, ethics, common sense, organization ability, and strong proven maturity -- all qualities which have accounted for achievement among centuries of leaders.

There is a danger in our society that we may see prestigious acceptances or high test scores as a measure of success in life. Parents can assure their sons or daughters of individual worth and of a uniqueness truly their own.

And, parents, gird up. Tuition bills follow shortly.