You should definitely bring your own mattress cover.

“You should definitely get a mattress pad before you come, or plan to purchase one when you move in. There are different styles (eggshell, foam, stuffed, etc.) and fittings (none, elastic straps, fitted like a sheet). You should know, though, that all beds at RPI require Extra-long twin sheets. You should find these in Target closer to August or in linen stores year-round.” [from a question Summer 2010]