The rapid growth in popularity of social media has led to various theoretical discussions and empirical investigations on the potential benefits of their use. Social media represents an important developmental context for the handling of issues which are characteristic of adolescence such as gender and identity exploration, self-expression, and the increased need of peer acceptance (Gerwin, Kaliebe, & Daigle, 2018). Social media also allows users to overcome permanent real-life issues (eg, physical disabilities) and age or work-related barriers (eg, geographical distance to family members), helping some adults to satisfy the need to maintain social contact. Despite various advantages, evidence indicating some dysfunctional qualities of social media use have also stimulated hypotheses regarding the possibility that frequent use might hide a behavioral addiction (M�ller et al., 2016). Other authors argue against this perspective by suggesting that an excessive use of social media might be an expression of pre-existing psychopathology (eg, social anxiety or depression) rather than primary disorders (Shaffer, Hall, & Vander Bilt, 2000). Finally, some authors recommend a dose of skepticism towards the idea that frequent social media use might indicate a disorder or even only a mere symptom of a different primary condition, suggesting to systematically assess motivations for use as these might reflect a temporary compensatory strategy to cope with transient negative states (Kardefelt-Winther, 2014). These conflicting positions, however, converge upon the fact that an excessive use of social media, which we can term problematic social media use (PSMU), can have negative consequences in daily life. The purpose of this special issue is to provide a forum for the presentation of contemporary research on PSMU with the hope to help readers to identify promising areas for future research and clinical advances.