Concerns about the problematic nature of internet use have been discussed since the inception of the internet. Internet addiction, problematic internet use (PIU), and the deficient self-regulation of internet use are some issues studied in this domain. Some regard these conditions as genuine disorders that cause disruptions in one’s life. Others criticize their legitimacy, claiming that functional impairment associated with internet use is indicative of primary psychosocial problems and has little to do with the internet. The purpose of this investigation was to understand whether cognitive preoccupation and uncontrolled use, components of PIU, are part of a unique disorder or are symptomatic of underlying psychosocial problems. This research tested the mediating role of PIU in the relationships between psychosocial problems (i.e., social anxiety, loneliness, and depression) and impairment of interpersonal relationships and vocational performance in two studies. Different conclusions were reached based on the methodological design of the study; however, the findings generally supported the mediation of PIU.