For the first time, the Diagnostic and Statistical Manual for Mental Disorders (DSM-5) introduces non-substance addictions as psychiatric diagnoses. The aims of this paper are to (i) present the main controversies surrounding the decision to include internet gaming disorder, but not internet addiction more globally, as a non-substance addiction in the research appendix of the DSM-5, and (ii) discuss the meaning behind the DSM-5 criteria for internet gaming disorder. The paper also proposes a common method for assessing internet gaming disorder. Although the need for common diagnostic criteria is not debated, the existence of multiple instruments reflect the divergence of opinions in the field regarding how best to diagnose this condition. We convened international experts from European, North and South American, Asian and Australasian countries to discuss and achieve consensus about assessing internet gaming disorder as defined within DSM-5. We describe the intended meaning behind each of the nine DSM-5 criteria for internet gaming disorder and present a single item that best reflects each criterion, translated into the 10 main languages of countries in which research on this condition has been conducted. Using results from this cross-cultural collaboration, we outline important research directions for understanding and assessing internet gaming disorder. As this field moves forward, it is critical that researchers and clinicians around the world begin to apply a common methodology; this report is the first to achieve an international consensus related to the assessment of internet gaming disorder. © 2014 Society for the Study of Addiction.