The relationship of Internet behavior to sociability and aggression in real life was investigated in a web-based survey. Weblog users (n=395) and online-game users (n=206) were asked to respond to questionnaires that included their behavior on the Internet, as well as to scales that measured real-life sociability, aggression, and social isolation. Results indicated that Self-reflection on weblogs and Feeling of Belonging during online-games related to enhancement of sociability. By contrast, Internet behavior such as flaming, as well as immersive and addictive use, related to decrease of sociability and increase of aggression regardless of the type of application that was used. These findings suggest that the effects of weblogs and online-games use depend on the type of behavior, as well as the types of application, that are used. It is also suggested that social isolation in real life decreased sociability through immersive and addictive use, and increased aggression through flaming.