The fifth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) includes in its research appendix a potential new diagnosis-Internet gaming disorder. This article outlines the debate surrounding non-substance addictions and the rationale for including this condition in the "Conditions for Further Study" chapter in DSM-5 Section III. It also describes the diagnostic criteria that DSM-5 recommends and methods to assess Internet gaming disorder. The paper details international research related to prevalence rates, demographic, psychiatric, and neurobiological risk factors, the natural course of the condition, and promising treatment approaches. The paper concludes by describing important issues for research to address prior to official recognition of this condition as a mental disorder.