The Big-Five personality traits may influence people’s usage of social networking sites (SNSs), and that of children may not be the same as adolescents or adults. This study investigated the relationships between elementary school students’ personality traits and their usage of SNSs. Two hundred and forty 6th graders in Taiwan were involved in this work. The results indicated there were no gender differences in students’ SNS usage. Extraversion had a significantly positive relationship with SNSs’ usage for sharing, branding, monitoring, and learning. Emotional stability had a positive correlation with using SNSs for relaxing. Learning was the most frequent activity carried out on SNSs among the elementary school students examined in this work, and few of them used such sites for expressing, branding, sharing, or organizing.