Online games are very popular among adolescents in Korea. They sometimes lead to cyber delinquency. An ethnographic analysis was conducted in this study to address the social significance of online games. The results showed that the adolescents who were addicted to or indulged in the games were likely to commit delinquency online and/or offline. Delinquency in an information society is typically individualistic, whereas deviant behaviors in an industrial society are more social and collective, such as group violence. Parenting style, student-teacher relationship, peer pressure, game environment, and recreational facilities for the adolescents were intertwined with such adolescent delinquency. Finally, some implications of the online games from the perspective of social welfare practice were discussed to prevent online game indulgence and addiction and adolescent delinquency.