We conducted a study of the relationships between Internet self-efficacy, sensation seeking, the need for cognition, and problematic use of the Internet. The study was based on a randomly selected sample of 979 adult Internet users. Hierarchical multiple regression analysis of these subjects' responses on a questionnaire consisting of relevant items indicated that Internet self-efficacy and sensation seeking positively predicted problematic Internet use. Contrastingly, the need for cognition was significantly negatively associated with problematic Internet use.