Internet Gaming Disorder has been included as a preliminary diagnosis in DSM-5. The question remains, if there are additional internet activities related to addictive use. Especially, use of social networking sites has been discussed to be related to excessive use, but only few empirical studies are available. We wanted to explore, if use of social networking sites is related to addiction symptoms and psychosocial distress and which variables (demography, personality) predict addictive use. A representative sample of n = 9173 adolescents (12-19 years) was enrolled. Self-report questionnaires assessed demography, frequency of social networking sites use, internet addiction, personality, and psychosocial distress. Gender-specific associations were found between frequency of use of social networking sites and addiction criteria, especially regarding preoccupation and loss of control. Adolescents using social networking sites intensely were more often classified with internet addiction (4.1% boys, 3.6% girls) and displayed higher psychosocial distress. Frequency of social networking sites use and its addictive use were predicted by similar variables except for extraversion that was only related to frequency of use. Since the intense use of social networking sites can be related to addictive symptoms and is accompanied by psychosocial distress it might be considered as another form of addictive online behavior.