The purpose of the present study was to examine the relations of children’s emotion knowledge (and its components) and socially appropriate behavior to peer likability in a sample of Italian preschool children at two time-points. At both Time 1 (T1; n = 46 boys, 42 girls) and a year later at Time 2 (T2; n = 26 boys, 22 girls), children’s emotion knowledge (i.e., emotion recognition, situation knowledge) was assessed, teachers evaluated children’s socially appropriate behavior, and peer likability was measured using a sociometric procedure. A two-wave autoregressive cross-lagged model indicated that children’s T1 emotion recognition was associated with higher T2 socially appropriate behavior, and children’s T1 socially appropriate behavior was related to higher T2 peer likability, even after controlling for stability in the constructs. Socially appropriate behavior mediated the relation between preschool children’s emotion recognition and peer likability. No bidirectional associations were found. The results support the notion that teacher training should focus on promoting children’s emotion knowledge to create a classroom atmosphere characterized by positive social behaviors and harmonious peer relationships across the preschool years.