The project examines the buffering role of student-teacher relationship in Head Start populations. The three major objectives of the research are: 1) to describe the chronic stress experienced by children attending Head Start and investigate how chronic stress impacts their cortisol reactivity to a stress paradigm; 2) to examine the relation between children's cortisol reactivity and child behavior problems and social competence; and 3) to investigate the moderating role of teacher relationships on the relation between children's cortisol reactivity, behavior problems, and social competence. The study findings will help identify chronic stressors that may be particularly harmful to children's cortisol reactivity. Understanding the role student-teacher relationships may play in moderating this risk will show how physiological risk may be reduced by supportive environmental factors that can be provided through Head Start.