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, the authors 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. The authors hypothesize that this pattern of class assignments results, in part, from power relations among teachers within a school, a process that works to disadvantage those with less experience and from minority and female backgrounds, as well as from parental pressures. These patterns have negative implications for teacher retention given the importance of working conditions for teachers' career decisions. Teacher Value-Added Estimation is appended. (Contains 3 figures, 10 tables, and 8 footnotes.)