As Internet use grows, so do the benefits and also the risks. Thus, it is important to identify when individuals' Internet use is problematic. In the present study, 449 participants aged from 16 to 71 years of age were sourced from a wide range of English-speaking Internet forums, including social media and self-help groups. Of these, 68.9% were classified as nonproblematic users, 24.4% as problematic users, and 6.7% as addictive Internet users. High use of discussion forums, high rumination levels, and low levels of self-care were the main contributing factors to Internet addiction (IA) among adolescents. For adults IA was mainly predicted through engagement in online video gaming and sexual activity, low email use, as well as high anxiety and high avoidant coping. Problematic Internet users scored higher on emotion and avoidance coping responses in adults and higher on rumination and lower on self-care in adolescents. Avoidance coping responses mediated the relationship between psychological distress and IA. These findings may assist clinicians with designing interventions to target different factors associated with IA.