Research Findings: This study examines whether specific teacher instructional practices in early education are associated with children's engagement in prosocial behavior. Teachers' verbal encouragement of prosocial behavior and empathy, emotional warmth, positive behavior management, vocabulary instruction, and encouragement of expressive language were explored in relation to children's classroom prosocial behavior. We also examined whether increased prosociability was evident in the classrooms of teachers who both encouraged prosocial behavior and empathy "and" demonstrated emotional warmth. We observed 124 first-grade classrooms that included 2,098 children. Results indicated that teachers' verbal encouragement of prosocial behavior and empathy was most strongly associated with classroom prosocial behavior. There was also a significant association between encouragement of expressive language and prosocial behavior. Emotional warmth, positive behavior management, vocabulary instruction, and the joint effect of teacher emotional warmth and encouragement of prosocial behavior and empathy was not associated with prosocial behavior. Practice or Policy: These findings suggest that teachers' more deliberate encouragement of prosocial and empathic behavior and their creation of a positive, interactive social environment may support students' prosocial behavior. The implications of these findings are particularly important for young children learning to engage with others. (Contains 4 tables.)