If other schools you have applied to or plan to apply to require subject tests, then by all means take the required subject tests, BUT NAVY is interested in ONLY the math and verbal test results. While on this subject, do yourself a big favor and take both the SAT and the ACT exams - you might discover one is better for you than the other. Plan to take the exams more than once, NAVY super scores so there is no penalty for taking the exams multiple times. Start early - personally I recommend starting the exams in your sophomore year so you have time to boost your scores to the max by the middle of your senior year when NAVY shuts off further scores. Keep taking the exams until you are comfortable that you've gotten the best scores you are likely to attain - DON'T use the median scores in the class profile brochure as a guide, you really need to get your math scores over 700 (SAT) or 30 (ACT), and even at those levels there is no guarantee that someone on your slate won't outdo you. Keep in mind that the SA's all started out as engineering schools, and that they award Bachelor of Science degrees regardless of your major - consequently you should expect a ton of math, science, and engineering courses your first two years. That also should explain why there is such a focus on the math exams.