We’re often asked by families how much weight the college essay carries in the admissions process, many of whom are wondering if a great essay can help a student overcome application weaknesses like grades or test scores that fall below the average for a particular college.

The answer certainly depends on the college. While there’s no specific weighting of essays in the college admissions process, you can understand their role if you think of the application and the essay as two distinct parts of the evaluation, serving different roles.

The application is where an admissions officer decides if you are qualified for admission. What classes did you take? What were your grades? What were your test scores? What were your activities? What honors or awards did you receive? What did your teachers say about you in their letters of recommendation? Could you be academically and socially successful on campus, the kind of student who will make an impact during your four years on campus?

If the answers to those questions work in your favor and there is plenty of room for students like you on campus, then the essay is less important. Put another way, if the committee doesn’t need to turn away qualified applicants, then the essay is not as important.

But the more selective the college, the more qualified students there will be in the pool, and often without enough space to accommodate them. In fact, the most selective colleges may receive two or three times the number of applications from high school valedictorians than they could ever admit. In cases where there are too many qualified applicants and not enough spots, admissions officers have to make distinctions about students that go beyond those qualities listed on an application.

Do I like you? Do I think students will like you? Do I think you have an interesting perspective to bring to campus? Will students and faculty feel like their experience benefits from having you in the classroom, in the dorm, in the clubs, and in the campus organizations?

Those distinctions are best answered by honest, revealing essays that help admissions officers get to know you.

An effective college essay helps an admissions officer get to know you in ways that an application cannot. It makes them like you and picture you on campus. And most importantly, it gives them a reason to choose you as one of those students that they will bring to committee to make a case for admission.

Essays rarely change an admissions officer’s mind if your qualifications aren’t up to the college’s standards. When essays do sway the vote in those cases, it’s usually because they reveal a significant hardship or other life circumstance that explains the inconsistencies. If you had such a situation that affected you, that might be worth sharing in your essay and an admissions committee will consider it. But please be careful. Most essays that attempt to explain away deficiencies, often by manufacturing hardship that wasn’t actually there (“My friend’s parents divorced and it affected me, which is why my grades dropped sophomore year,”) just serve to highlight the areas of an application that a student was trying to explain away.

More commonly, a great essay takes you from being just another kid among many with great qualifications and moves you to an applicant an admissions officer will lobby for. They’ll share your story and their vision for why they believe you deserve a spot on campus. And at the more selective colleges, that’s about the best you can reasonably hope for in this process—one person who’s convinced, who will make an effort to convince the rest of the committee.

So yes, the essays are important. The colleges read them and often use them to drive decisions that couldn’t be made with just grades and test scores alone. So give your essays the time and attention they deserve, but also, have reasonable expectations about how much even the best essay can accomplish. The best way to do that is to apply to plenty of schools where your chances of admission are strong rather than playing the “reach school” lottery and applying to a dozen schools where your chances aren’t as encouraging.

If you pair good college choices with good applications and essays, you’re likely to be happy with your results.