IntroductionMaladaptive cognitions – irrational beliefs and thoughts about the self, the real and virtual worlds – are part of the variables, which explain the development and the maintaining of gaming addiction. However, no French instrument had yet been fully designed and validated to assess these cognitions. ObjectiveThe present study aimed to adapt and validate, in French, such an instrument: the Internet Gaming Cognitions Scale (IGCS). Method and ResultsThis scale is composed of 24 items and 4 factors assessing maladaptive cognitions among players – beliefs about game reward value and tangibility, maladaptive and inflexible rules about gaming behaviour, over-reliance on gaming to meet self-esteem needs and, finally, gaming as a method of gaining social acceptance. In the present study, the IGCS was back-translated, adapted and validated in several steps. Firstly, two bilingual individuals back-translated the English scale. Committee analysis, clearness and validity assessing allowed us to design a clear and faithful French version. Secondly, exploratory factor analysis (n=262) was conducted to determine the new structure of the scale, which was statistically and theoretically valid. Nine items had to be removed from the original version. Actually, five factors – with 15 items left – were identified: positive emotions, need of completion, cognitive salience, virtual comfort and need of social recognition. Thirdly, acceptable and/or satisfactory MacDonald's Omegas confirmed the identification and the relevance of these five factors. Fourthly, confirmatory factor analyses (n=187) were conducted to validate the structure with satisfactory fit indices: RMSEA=.055, RMR=.027, GFI=.917, CFI=.939. Only Chi2 was unsatisfactory, but was compensated for by good TLI (.92) and IFI (.94). Fifthly, correlations allowed us to conclude that our scale had a good construct validity showing previously demonstrated links with other variables (weekly gaming time, addiction). Convergent validity was also found with similar constructs. The latter were assessed through the assessment of cognitions, emotions, and behaviours involved in gaming. Finally, test–retest reliability was assessed (n=27), concluding with a good consistence across time (r=.94, P<.001). ConclusionThe present study allowed us to design and validate a French scale, which assesses gamers’ maladaptive cognitions and shows good psychometric attributes. This scale would be very useful in research and practical fields, knowing how much maladaptive cognitions play a role in the development and the maintenance of gaming disorder.