Pathological use of computer and video games has been associated with indicators of psychosocial well-being, such as loneliness, low self-esteem, low social competence, and low life satisfaction. However, few studies have decisively demonstrated whether these indicators of psychosocial well-being are causes or consequences of pathological gaming. To address this gap in the literature, we conducted a two-wave panel study among 851 Dutch adolescents (543 gamers). Causal relations were analyzed using autoregressive structural equation models. These analyses indicated that social competence, self-esteem, and loneliness were significant predictors of pathological gaming six months later. Thus, lower psychosocial well-being can be considered an antecedent of pathological gaming among adolescent gamers. Our analyses further indicated that loneliness was also a consequence of pathological gaming. This suggests that displacement of real-world social interaction resulting from pathological use of video games may deteriorate existing relationships, which could explain the increase in adolescent gamers’ feelings of loneliness.