Online gaming addiction is a topic of increasing research interest. Since the early 2000s, there has been a significant increase in the number of empirical studies examining various aspects of problematic online gaming and online gaming addiction. This entry examines the contemporary research literature by analyzing (1) the prevalence of problematic online gaming use and online gaming addiction; (2) the negative consequences of excessive online gaming; (3) the factors associated with problematic online gaming and online gaming addiction; and (4) the treatment of problematic online gaming and online gaming addiction. The entry concludes by looking at the trends in the field and a consideration of what the future of online gaming addiction might be.