Young people are increasingly using social networking sites (SNSs) like MySpace and Facebook to engage with others. The use of SNSs can have both positive and negative effects on the individual; however, few studies identify the types of people who frequent these Internet sites. This study sought to predict young adults' use of SNSs and addictive tendency toward the use of SNSs from their personality characteristics and levels of self-esteem. University students (N = 201), aged 17 to 24 years, reported their use of SNSs and addictive tendencies for SNSs use and completed the NEO Five-Factor Personality Inventory and the Coopersmith Self-Esteem Inventory. Multiple regression analyses revealed that, as a group, the personality and self-esteem factors significantly predicted both level of SNS use and addictive tendency but did not explain a large amount of variance in either outcome measure. The findings indicated that extroverted and unconscientious individuals reported higher levels of both SNS use and addictive tendencies. Future research should attempt to identify which other psychosocial characteristics explain young people's level of use and propensity for addictive tendencies for these popular Internet sites.