To better connect emotional development and social cognition literatures, in this study, the intersection of preschoolers' emotion and behaviour response choices to hypothetical peer conflicts was examined among 305 4.5-year-olds in private childcare and Head Start. Latent class analyses identified five subgroups of children with connections between their emotion and behaviour response choices (happy/passive, sad/socially competent, angry/passive, angry/aggressive, and sad/passive). Subgroup membership differed across genders and economic risk statuses and was also a predictor of early school success (i.e. social competence, classroom adjustment, and academic readiness). Overall, even after accounting for the associations between known predictors of young children's behavior and school success (i.e. gender and socioeconomic status), membership in the subgroups in preschool was uniquely predictive of both concurrent and later social competencies, classroom adjustment, and academic readiness. Furthermore, preschool social competence partially mediated contributions of subgroup membership in kindergarten classroom adjustment. These findings are discussed in relation to existing social information processing and emotional development literatures, including potential implications for understanding young children's early school success. (author abstract)