Research suggests that online communication is associated with increased closeness to friends and friendship quality. Children under 13 years of age are increasingly using social networking sites (SNSs), but research with this younger age group is scarce. This study examined the relationship between SNS use and feelings of belonging among children aged 9-13 years. A self-report questionnaire was administered to 443 children (48.98% boys), asking about their SNS use and their sense of belonging to their friendship group. SNS users reported a stronger sense of belonging to their friendship group than non-users, but this was found only among older boys. Furthermore, among boy SNS users, a positive linear relationship was found between the intensity of usage and feelings of belonging. No significant relationships were found for girls. These findings suggest that boys who use these sites are gaining friendship benefits over and above those boys who are non-users or low-intensity users. Longitudinal studies should investigate the causal relationships between SNS use and social effects within this age group. (Contains 2 tables and 2 figures.)