This study examines young children's career aspirations, gender differences in those aspirations, and children's perceptions of the amount of math and science used in careers. We asked 1634 students in first to third grades what job they wanted in the future and how much they thought they would use math or science in it. Career aspirations were sorted into 27 career categories, of which 12 showed significant gender differences. Notably, boys were more likely to indicate military, manual labor, and math/computer science careers, and girls were more likely to indicate stay at home parent, education, and animal care careers. Students aspiring to science, technology, engineering, and mathematics (STEM) careers thought they would use science, but not math, more than non-STEM-aspiring students did. School counseling interventions focused on specific STEM subfields, and education highlighting links between school subjects and careers requirements may benefit students and reduce gender inequality in STEM fields.