||The breadth and depth of a child's vocabulary seem to be key predictors of cognitive outcomes. Certain contexts such as shared-book reading, and certain parenting behaviors such as parents' verbal responsiveness, appear to be related to how quickly children develop their vocabulary. The current study tested whether teachers' responsiveness during shared-book reading also contributes to children's vocabulary outcomes. A measure of teacher responsiveness in group settings was developed and 15 preschool teachers were observed during shared-book reading sessions. In addition, children in each of the teacher's classrooms were assessed for vocabulary breadth. No relationship was found between teacher responsiveness and the vocabulary scores of children in their classrooms. Potential explanations for why this relationship was not detected and future directions are discussed.