As part of a larger longitudinal project on the assessment of preschoolers' social-emotional development, children's social information processing (SIP) responses to unambiguous hypothetical situations of peer provocation were assessed for 239 preschoolers from Head Start and private childcare settings. SIP measurement focused on emotions children would feel during these situations, and their behaviour response decisions. The aims of the study were to examine foundations of these SIP responses in self-regulation and emotion knowledge, as well as to consider how adaptive SIP responding predicted concurrent classroom adjustment and pre-academic preacademic literacy. Using a PLS modelling procedure, results showed that both self-regulation and emotion knowledge were associated with adaptive SIP responding. Moreover, adaptive SIP responding predicted classroom adjustment and pre-academic preacademic literacy. Discussion centres on the contribution of social-emotional competence to preacademic literacy.