Past experimental research has shown that violent video game exposure can increase aggression-related variables compared to nonviolent video game exposure. Currently, there are two competing hypotheses to interpret these findings. The violent-content hypothesis states that violent video games increases aggression because the violent content increases the accessibility of aggression-related knowledge structures. The competition-only hypothesis states that violent video games typically have a high level of competition compared to nonviolent video games. According to this hypothesis, the heightened level of competition increases aggression. One way to test these hypotheses is to expose participants to violent and nonviolent video games matched on competition. Four experiments accomplished this by examining the impact of illicit violence in sport video games on aggression-related variables. Experiment 1 demonstrated that the illicitly violent sport video games contained more violence than the nonviolent same-sport video games, but were not significantly different on competitiveness. In the remaining experiments, participants played either a violent or nonviolent sports video game. Participants then completed measures assessing aggressive cognitions (Experiment 2), aggressive affect and attitudes towards aggression in sports (Experiment 3), or aggressive behavior (Experiment 4). Exposure to violent sports video games increased aggressive affect, aggressive cognition, aggressive behavior, and some positive attitudes towards aggression in sports. Because all games were competitive, these findings support the violent-content hypothesis and fail to support the competition-only hypothesis.