We use ECLS-K data from a national sample of students to estimate the determinants and
consequences of reading ability group placement in kindergarten and first grade. We find
that prior test score performance is the strongest determinant of such placement, followed in
magnitude by the teacher's judgment of the student's learning-related classroom behavior.
These variables explain most of the race, gender, and social class differentials when
students are placed into ability groups for the first time. Within kindergarten and first grade …