St. Jude's School for Boys is an elite private school located on the Upper East Side of Manhattan. It is the school that the leading male characters in Gossip Girl are attending or have attended in the past. It is run by Mr. Prescott and also is the sister school of the Constance Billard School for Girls.
In season one, Dan Humphrey, Chuck Bass, Nate Archibald, and Eric van der Woodsen go to St. Jude's. Nate, Chuck and Dan are first shown on a bus ride to school. It is shown that at St. Jude's there is a social hierachy but not as much as at Constance Billard. Nate is dating Blair, and Chuck is the good-timer who parties, drinks and sleeps around. Dan, on the other hand is just like his sister - an unknown normal boy in a world of posh parties and upper-class students.
With the older crowd moving into Senior year the question is about colleges. However Eric is now a sophomore and is still best friends with Jenny and dating Jonathan. With the St. Jude's boys leaving at the end of the year they go off to college.
Eric is the only boy left at St. Jude's out of the main cast. He has problems at school, Jonathan and Eric have to put up with problems from Jenny and the mean girls. St. Jude's isn't shown as much in Season 3 as in the previous two seasons.
St. Jude's isn't shown in season four, although Eric and Jenny are both in Senior Year now. Jenny is in Hudson and we don't see them going to school.