What race/ethnicity am I?

either way you seem to be covered, so I wouldn't stress about it. This seems to be a bit of an issue in the USA - I'm asuming PSAT involves American residency? - so you could get away with ticking both boxes and adding a covering note expaining your unique cirstances. Shame you don't appear to be applying for educational status in Britain, as being Italian means you'd get in as of right - Common Market country and European partner. (but don't stress Nicaraguan - Central Americans, except for one former British colony, get no special visa rights). BTW , have you thought of applying for the equivalent Italian course by right of nationality, if the American immigration people get stroppy? Residency in Italy plus Italian pport means you could use it to get into Britain or Ireland, if going to an English-speaking country is important to you.