: Internet gaming disorder (IGD) is characterized by signs and symptoms similar to substance use and gambling disorders, and associated with psychosocial impairments. Research suggests that maladaptive gaming-related cognitions and coping may be implicated in IGD; therefore, interventions for IGD need to target these underlying mechanisms. Mindfulness-based treatment is effective in changing maladaptive cognitive processes and increasing adaptive coping among people with addictions.: This study used data from an RCT of Mindfulness-Oriented Recovery Enhancement (MORE) for IGD to further examine changes in maladaptive gaming-related cognitions and positive reappraisal as mediators of the effects of MORE on IGD signs/symptoms.: Participants (= 30, Age= 25.0, = 5.4) were randomized to 8-weekly sessions of MORE or a support group (SG) control condition. IGD severity, levels of craving for video game playing, maladaptive gaming-related cognitions, and positive reappraisal were measured at pre-and posttreatment, and 3-month follow-up.: Multivariate path analyses revealed that effects of MORE in reducing IGD and craving were statistically mediated by changes in maladaptive gaming-related cognitions. Though changes in positive reappraisal did not significantly mediate effects of MORE on IGD or craving, MORE enhanced positive reappraisal to a significantly greater extent than the SG at posttreatment.: Findings suggest that effects of mindfulness treatment in reducing maladaptive gaming-related cognitions might lead to reductions in IGD severity and cravings for video game playing. This cognitive mechanism should be evaluated in a future, full-scale RCT. Background Aims Methods N M SD Results Discussion