Emotion knowledge supports early school success. Socializers' emotions, contingent reactions to emotions, emotion language, and beliefs about emotions can contribute to preschoolers' emotion knowledge, but more is known about parents' contributions than teachers'. We expected teachers' emotion socialization findings to parallel those in the parent literature, with potential moderation by classroom-level socioeconomic risk. Participants included 85 teachers and 327 preschoolers in high or low socioeconomic risk classrooms. Children's emotion knowledge was assessed twice. Teachers reported on emotional expressiveness, reactions to children's emotions, and emotion socialization beliefs. Their emotion language during book reading was codified. Hierarchical linear models predicted end-of-year emotion knowledge via emotion socialization, risk, and their interactions, controlling for child age, gender, and beginning-of-year emotion knowledge. Only one finding resembled the parent literature; most were specific to high socioeconomic risk classrooms, highlighting the importance of context in emotion socialization. Applications, limitations, and suggestions for future research are considered. (author abstract)