Problematic video gaming (PVG) is a concern for psychologists attending children and adolescents. Uniform diagnostic criteria are lacking, and risk factors are poorly understood. Internet gaming disorder (IGD) was included in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), and scales derived from its diagnostic criteria may be helpful to assess PVG. A multicenter study was conducted in secondary schools using an IGD-derived scale (dichotomous Nine-Item Internet Gaming Disorder Scale [IGD-9]), analyzing PVG-related variables. Seven hundred eight students (55.8 percent male) with mean age 15.6 ± 2.7 years were included. Seventy-three percent were gamers and 22 percent heavy gamers (HGs). Forty-five percent reported online gaming and 6.6 percent massive multiplayer online role-playing games (MMORPGs). Fifty-nine students (8.3 percent) scored 5 or more in IGD-9 and were classified as IGD+. HG and IGD+ subjects were more frequently male and online and MMORPG gamers (p < 0.01). However, IGD+ subjects had significantly worse psychosocial scores than IGD- (p < 0.001), while HGs did not significantly differ from casual gamers (p > 0.01). The multivariate analysis showed that IGD+ scores were significantly associated with worse psychosocial health and adjustment (p < 0.001), while the other variables (male sex, online and MMORPG gaming, and HG) were not significantly associated (p > 0.01). The IGD-9 scale scored positive in 8.3 percent of our sample. Unlike gaming time, this scale was associated with psychosocial disturbances, making it potentially useful as a screening method to detect candidates for clinical intervention.