The present short-term longitudinal study examined the stability and role of peer influence on both physical and relational aggression in early childhood using a dyadic data analytic framework. Following the peer-individual interaction model, forms of aggressive behavior (i.e., physical and relational) were observed in 43 dyads of close friendships in early childhood (M = 47.37 months, SD = 7.56) to better understand how friendships may maintain aggressive behavior over time. Friendship quality (FQ) was included as a moderator to explain how friendships may maintain aggression. The results provide evidence supporting the affiliation hypothesis for physical aggression with opposite findings for relational aggression. Negative FQ moderated associations with both relational and physical aggression over time whereas positive FQ moderated the dyadic influence with physical aggression over time. Limitations and future directions are discussed.