The purpose of this proposal is to examine whether variability in the quality of teachers' interactions (Emotional Support, Classroom Organization, Instructional Support) with students is systematically related to the children's development. In other words, the authors examine whether the amount that teachers vary over the course of a day is a characteristic of the teacher by seeing if there are systematic associations between teachers' variability and children's development. If variability is simply error, they would not expect the associations to be systematically related to children's development. However, if a pattern emerges, it would support their notion that variability is itself characteristic of the classroom. (Contains 1 table.)