Peer acceptance represents the degree to which a child is well liked by peers, and it is a crucial component of the early childhood years (Ladd & Sechler, 2013). Being accepted among peers impacts multiple areas of child development, including academics, behavior, and socialemotional domains. A child who is highly accepted by their peers is viewed as a preferred playmate and can be observed playing with various peers. Young children's earliest peer relationships begin forming during the preschool years. One predicting factor of peer acceptance is the attachment relationship between the parent and child. The security experiences within parent-child attachment relationships help foster the growth of children's social competence, which in turn allows children to begin forming relationships with other children (Raikes, Virmani, Thompson, & Hatton, 2013; Thompson, 2016). Another important predictor of peer acceptance is children's self-regulation, which includes several cognitive and behavioral processes that allow children to manage their emotions, behavior, and thoughts to better acclimate to their environment (Liew, 2012). Self-regulation is linked to both the parent-child attachment relationship and children's peer acceptance (Contreras, Kerns, Weimer, Gentzler, & Tomich, 2000; Gottman & Mettetal, 1986). The purpose of this study was to test the mediating role of preschoolers' self-regulation on the association between parent-child attachment relationship qualities and preschoolers' peer acceptance. Three mediation models were tested via a structural equation modeling approach using path analysis. In the first mediation model, it was predicted that the model will represent the best fit for the data collected, supporting that children's (girls and boys combined) self-regulation mediates the relation between the parentchild attachment relationship qualities and preschoolers' peer acceptance. Results from the first mediation model indicated that preschoolers' self-regulation mediates the relation of parent-child attachment qualities and preschoolers' peer acceptance. In the second mediation model, it was predicted that older preschoolers will demonstrate stronger self-regulation, compared to younger preschoolers. Results from the second mediation model indicated that children's age significantly predicts preschoolers' self-regulation. In the third mediation model, with sufficient statistical power, it was predicted that girls will demonstrate stronger self-regulation, compared to boys. Results from the third mediation model indicated that children's gender significantly predicts preschoolers' self-regulation. These results contribute to the literature regarding factors that predict peer acceptance and have important implications for children, families, early childhood education teachers, and other professionals who support young children's overall development.