The purpose of the present study was to investigate the impact of social networking sites (SNS) on cognitive abilities and reported levels of social connectedness in adolescents. In order to provide a reliable measure of cognitive skills, standardized tests of verbal ability, working memory, and academic attainment were administered. Students also responded to questions about the length and type of social media use (Facebook, YouTube, and Twitter). The findings indicated that young people who had used Facebook (but not YouTube) for more than a year had higher scores in tests of verbal ability, working memory, and spelling, compared to their peers who had used it for a shorter time period. The type of Facebook activities seemed to have an impact, as regression analyses confirmed that checking a friend's status updates was a significant predictor of verbal ability scores. However, regular or "active" engagement with SNS (each hour versus once a month) did not make a difference to their cognitive scores. Longer Facebook use, but not YouTube, was linked to higher reported levels of social connectedness. This pattern of results is interpreted in light of previous research, as well as the key physiological and social developments that occur during the adolescent period. (Contains 2 tables.)