While prior research has documented differences in the distribution of teacher characteristics across schools serving different student populations, few studies have examined how teacher sorting occurs within schools. Comparing teachers who teach in the same grade and school in a given year, we find less experienced, minority, and female teachers are assigned students with lower average prior achievement, more prior behavioral problems, and lower prior attendance rates than their more experienced, white and male colleagues. Though more effective (higher value-added ) teachers and those with advanced degrees are also assigned less difficult classes, controlling for these factors does not eliminate the association between experience, race, gender, and assignments. These patterns have negative implications for teacher retention given the importance of working conditions for teachers' career decisions.