The objectives of this study were to analyze the psychometric properties of the Generalized Problematic Internet Use Scale 2 (GPIUS2) and to examine the cognitive-behavioral theoretical model of problematic Internet use in a sample of 1491 Mexican adolescents (47.6% female, mean age = 14.51). Results showed that the GPIUS2 has adequate construct and convergent validity and internal consistency. Consistent with the hypotheses put forth by the cognitive-behavioral model, the findings indicate that preference for online social interaction and the use of the Internet for mood regulation increased the probability of reporting deficient self-regulation (i.e., compulsive Internet use and cognitive preoccupations with Internet use), which, in turn, was significantly associated with negative life outcomes. The fit of the model was adequate both for males and females, and there were no significant differences between them. Lastly, we discuss the contributions of this research to this field of study. (Contains 3 figures and 3 tables.)