The aim of this study was to examine the prevalence of Internet addiction in a nationally representative sample of college students and to identify any associated psychosocial risk factors. The present study was constructed using a cross-sectional design with 3,616 participants. Participants were surveyed during the middle of the spring and fall semesters and recruited from colleges around Taiwan using stratified and cluster random sampling methods. Associations between Internet addiction and psychosocial risk factors were examined using stepwise logistic regression analysis. The prevalence of Internet addiction was found to be 15.3 percent (95 percent confidence interval, 14.1 percent to 16.5 percent). More depressive symptoms, higher positive outcome expectancy of Internet use, higher Internet usage time, lower refusal self-efficacy of Internet use, higher impulsivity, lower satisfaction with academic performance, being male, and insecure attachment style were positively correlated with Internet addiction. The prevalence of Internet addiction among college students in Taiwan was high, and the variables mentioned were independently predictive in the logistic regression analysis. This study can be used as a reference for policy making regarding the design of Internet addiction prevention programs and can also aid in the development of strategies designed to help Internet-addicted college students.