This paper reports on a study that examined teachers' perceptions of their relationships with specific students, their experience of stress in relation to those students, and whether those perceptions and experiences translate into observable differences in actual teacher behavior toward those students in the classroom. Specifically, the project explored the validity of two teacher-pupil relationship measures, the Index of Teaching Stress (ITS) and the Student-Teacher Relationship Scale (STRS), for predicting observed teacher behavior toward pupils. Teachers (N=30) from two Virginia middle schools completed three questionnaires regarding their relationships with both a behaviorally challenging and a control student in their classroom. Data analysis revealed that teacher behavior toward the behaviorally challenged child involved more negative and neutral behaviors than toward the control child, while the amount of positive behavior toward each child was not significantly different. Teachers experienced more stress with the behaviorally challenging child than with the control child and as stress increased, they tended to be less engaged with the behaviorally challenging child. Teachers also perceived greater warmth, less conflict, and more positive relations with the control child. Study findings suggested that teachers have different perceptions of and experience different stress levels with regard to specific students in their classroom, and that these differences may bias their behavior toward these students. Seven data tables are attached. (ND)