Research Findings: The current study is an examination of children's temperament as a predictor of their interactions with peers in preschool, with a particular focus on children's regulatory temperament characteristics (i.e., inhibitory control and attentional focusing) as moderators of associations between shyness and interactions with peers. Participants were 40 children (19 boys) ages 3 to 5 years enrolled in 8 different preschools in a midwestern city in the United States. Temperament was assessed via parent report when children were approximately 3 years old, and peer interactions were assessed via observations of children during the preschool day (using the Individualized Classroom Assessment Scoring System; J. T. Downer, L. M. Booren, O. K. Lima, A. E. Luckner, & R. C. Pianta, 2010) when the children were 4 years old. Attentional focusing moderated the association between shyness and children's communication and conflict during peer interactions. Inhibitory control and attentional focusing were inversely related to peer conflict, and attentional focusing was positively related to sociability, communication, and assertiveness in peer interactions. Limitations of the current study and future directions are also discussed. Practice or Policy: Teachers can facilitate young children's peer interaction by recognizing children's regulatory and reactive temperamental characteristics.