Objective: Psychologists have warned about the disadvantages of overusing Internet and a new kind of addiction named Internet addiction. The present study intended to review the role of both sensation seeking (directly and indirectly, by mediation of attachment styles) and attachment styles (directly) in Internet addiction.
Methods: The present research was a cross-sectional study. Statistical population of the research was all the students studying Bachelor’s Degree course at the Faculty of Psychology and Educational Sciences of Allame Tabatabaei University. Of the total 420 individuals, 180 persons (35 men and 145 women) were selected as members through convenience sampling method. Zukerman’s Sensation Seeking, Collins and Read’s Attachment Styles and Young’s Internet Addiction” questionnaires were applied to collect data, which were analyzed through structural equation modeling using AMOS and SPSS 16.
Results: Findings demonstrated that the proposed model had adequate goodness-of-fit indices (CMIN/DF: 1.67, GFI: 0.991, RMR: 0.001, CFI: 0.961 & RMSEA: 0.031). Sensation seeking and attachment styles variables were directly related to Internet addiction. Meanwhile, sensation seeking predicted internet addiction indirectly. 
Conclusion: Considering the obtained results, sensation seeking, directly and indirectly, by mediation of attachment styles is related to Internet addiction and can predict it. Attachment styles variable also predicts Internet addiction directly.