You might be older and wiser now, but one thing remains the same as you move on to grad school: There's always another standardized test to take.

And by that, we don't mean the GRE general test, which is required by many grad schools — we're talking about the GRE Subject tests -- all six of them. These subject tests allow you to demonstrate your abilities in the subject area that you plan to focus on during your graduate degree program. There are six GRE Subject tests available: Biology, Chemistry, English Literature, Mathematics, Physics and Psychology.

It's important to note that GRE Subject tests are ONLY offered in April, September and October every year, so if you plan to take one or more of the tests, register and prepare accordingly. Also, this is not a cheap test, unfortunately. The GRE Subject test is $150, but don't let cost hold you back. Check here to find out if you are eligible for the ETS fee reduction program, which gives a 50 percent discount to qualifying test-takers.

Most top-ranked master's and PhD programs will require or “recommend" a GRE Subject test, while lower-ranked schools are much less likely to require a Subject test score. So if you're considering a competitive, top-ranked grad school program, it's often to your advantage to take the appropriate GRE Subject test. Of course, this only applies if your program is based on one of the six subjects offered -- if not, lucky you!

But what if a program simply states that a GRE Subject test score is only “recommended" and not “required"? Does that mean you can avoid the test?

"In the context of graduate admissions at top schools, the word 'recommended,' for all intents and purposes, means 'mandatory,'" said Paul Bodine, founder and president of Admitify.com. "If you are applying to a program you know to be selective, and it states that a GRE Subject score is merely 'accepted,' read that as meaning 'recommended' and take the test. It could give you the edge you need."

One more reason to take a GRE Subject test: If you don't have strong grades from college courses in your subject area, taking the test will give you another chance to demonstrate your abilities.

How Can I Skip the Test?

If your target graduate program does not mention the GRE Subject test at all on its requirements page, then there is usually no need to take the test. Just to be 100 percent sure, call the program admissions office and confirm this.

If your target school "recommends" the test but you cannot take it for some reason (lack of time to study, cost, test anxiety, etc), it will really help to have strong grades in your subject area and enthusiastic recommendation letters from relevant individuals who are familiar with your work in the subject area. You could also write an optional essay to explain why you could not submit a GRE Subject test score, Bodine adds. However, ETS does allow for testing with accommodations on the GRE Subject test if you have a documented disability or health-related need.

Don't forget that even if you decide against taking the GRE Subject test, you will most likely still be required to take the GRE general test to apply to most grad school programs.

How Will My Score Be Used?

Just as your SAT or ACT score was taken into consideration with all the other parts of your college application, the graduate program admissions committee also will not be admitting or rejecting you solely based on your GRE Subject test score. Some programs may use this score to gauge your areas of strength. For example, if you scored well in Biological and Cognitive subscores of the GRE Subject test in Psychology but not as well in the Clinical or Social sections, the committee may use this information to guide your coursework in the school's program. The GRE Subject score will be an important part of your admission, but only one among several.

Bodine explains that how much admissions committees weigh your score will depend on a variety of factors “such as the prestige and rigor of the undergraduate program you attended, how high or low your subject test score was, whether you're applying to a master's or more selective doctoral program, and even how glowingly your references write about you. Someone who has exceeded academic expectations for demonstrating expertise, like publishing articles or presenting at conferences, may be forgiven for submitting a good but not great subject score; she has demonstrated her expertise in other ways."

Test Prep Strategies

All of the six GRE Subject tests are two hours and 50 minutes long, without a break. The best way to prepare, as always, is to take a practice test before you do anything else. This will give you an idea of where you should focus your efforts. You can find practice tests (and test-taking strategies) for your subject here on the ETS website.

To refresh your skills, go back over your college class notes and review the relevant sections of your textbooks. There are many ways to study, but it depends on your style, your budget and how much time you have before the test date. You could enroll in a group class, hire a tutor or use online study guides and courses. If you know someone who is taking the same test, buddy up and study together.

But Bodine notes that “if you have invested 50 hours -- say, 10 hours a week for six weeks -- you have likely prepared very well, especially if you are taking the test relatively soon after completing your degree in your subject discipline."

As soon as you know which graduate programs where you'll be applying, find out if they require or recommend a GRE Subject test. If so, get a jump on your test prep while the material is still fresh!