An upperclassman is a student in the eleventh or twelfth grade of high school, or in the third or fourth year of college. Students in ninth and tenth grade, or in the first or second year of college, are called underclassmen.

Upperclassmen have more experience navigating school life than younger students. In high school, they might mentor freshmen, lead clubs, or serve as team captains. In college, upperclassmen have often declared their majors and know their way around campus. They may have figured out which professors give fair tests, where the best study spots are, and how to balance their workload.

The term carries a sense of seniority and responsibility. When teachers assign upperclassmen to help organize school events or guide new students, they're recognizing that these older students have wisdom to share. Being an upperclassman means you're no longer the newest person trying to figure everything out: you've learned the ropes, and now you can help others learn them too.