How Does Sibling Relationship Affect Children’s Prosocial Behaviors and Best Friend Relationship Quality?

The aim of this study was to explore whether the sibling condition (having a sibling) and sibling relationship quality affect prosocial behaviors and best friend relationship quality, deepening the mediating role of prosocial behaviors on the relationship between sibling relationship quality and best friend relationship quality. A sample of 310 children (161 males and 149 females) aged 8 to 11 years (M = 9.50, SD = 0.66) completed a battery of questionnaires. Results revealed that the sibling condition did not affect prosocial behaviors and best friend relationship quality. However, the quality of sibling relationships positively affected prosocial behaviors, which in turn positively influenced best friend relationship quality, supporting the mediator hypothesis. Limitations, strengths, and further development of the present study are discussed.