<p>At graduate level in sciences, most students do not pay tuition. They are, instead, paid a stipend and tuition is covered. In exchange for that, they work more than full time for the department, on experiments (sometimes involving travel far away from the grad. school itself, and for long periods of time) or teaching labs, grading exams, etc. It does seem like a good deal and it is if you are passionate about the subject. You have to remember, though, that it's not enough to live well on and that it may take five years or more of your life when your peers are earning full salaries. You will not have time to work to supplement the stipend, and you don't have summers off. Google the grad. student strikes at Yale if you want an idea of the 'down' side. If you've been paying four years of tuition for undergraduate school, it does come as a suprise to learn you can get a 'free' education. Nothing's really free, of course, you pay for it with sweat and years of your life. Not a bad deal if you are truly passionate about the subject, just be aware that it requires far more of your time and effort than earning a B.S. degree.</p>