In this study we investigated how early childhood teachers' emotion socialization behaviors contribute to children's social-emotional competence (SEC), as well as whether these contributions differ by culture. Participants included 117 teachers and 381 preschoolers in US or Italian classrooms. Teachers' and children's emotions and reactions to each others' emotions were observed within small group contexts, and children's SEC was assessed via observation of free play peer interaction and teacher ratings. As our first goal, we examined culture differences in teacher emotion socialization and in children's SEC with teachers and peers. Secondly, we investigated how teacher emotions and reactions to children's emotions contributed to variability in children's SEC with teachers and peers. Research Findings: Culture differences in children's and teachers' emotions and reactions to each others' emotions were found. Teachers' emotion socialization contributed to children's emotions and reactions to teacher emotion, as well as children's SEC with peers. Some findings resembled those in extant emotion socialization literature, but others were unique to our methodology, the preschool classroom, and/or children's culture. Practice and Policy: Ways in which the results add to theory and practice are discussed. Limitations and suggestions for future research are considered.