Children who have experienced maltreatment are at risk for a variety of negative outcomes, including various forms of psychopathology, academic failure, and especially, social difficulties with peers. In particular, maltreated children are more likely than nonmaltreated children to evidence higher rates of aggressive behaviors and lower levels of social competencies. The aims of the current study were to examine (1) whether young children with a history of maltreatment are more aggressive than their peers and are less-liked by their peers as they enter early elementary school, and (2) if children's behaviors (e.g., aggression) with peers mediate the relationship between maltreatment and social (peer) acceptance. It is hypothesized that maltreated children would evidence higher teacher ratings of aggressive behavior and be less-liked by their peers. Furthermore, it was expected that ratings of aggressive behavior would serve to mediate the relation between maltreatment and levels of social acceptance. This study used an existing database of maltreated children in early elementary school for whom there were complete teacher ratings of their aggressive behavior and peer group acceptance. The sample for the current study included 142 young children; 76 children of whom with a history of maltreatment prior to age 4, and 66 children who served as a non-maltreated comparison group. Results revealed that maltreated children were not only more aggressive but also less liked by peers, and that the level of peer-directed aggression mediated the relation between maltreatment history and social acceptance. The findings of this study support prior research indicating a strong relation between aggression behavior and being disliked by peers. The findings from this study also revealed an association between child maltreatment and levels of peer acceptance and that aggressive behavior serves to mediate the relation between early maltreatment and levels of peer acceptance. These findings have implications for social developmental theory and approaches for intervention.