This longitudinal study a) explored the similarity among children in primary school on physical and relational aggression in same-gender reciprocated friendship dyads and the socialization effects between the actor and the partner, and b) observed the presence of differences between female and male dyads. We identified 43 same-gender friend dyads and a comparison group of 69 same-gender non-friend dyads (50% female, aged 7 to 8 years [M=7.57; SD =0.32], who were reciprocal friends), from 5 schools located in Northern Italy. Actor-Partner Interdependence Model (APIM: Kashy & Kenny, 1999) was used to investigate friend similarity and socialization processes. Findings reveal: a) similarities between the two partners, especially in boys; b) no similarities in physical aggression but similarities in relational aggression in children who were friends compared to children who were not friends, especially for boys.
KEYWORDS: middle-childhood, friendship-dyad, similarity, physical and relational aggression, APIM