Violent video games glorify and reward immoral behaviors (e.g., murder, assault, rape, robbery, arson, motor vehicle theft). Based on the moral disengagement theory, we predicted that violent games would increase multiple immoral behaviors (i.e., lack of self-control, cheating, aggression), especially for people high in moral disengagement. High school students ( N = 172) who had completed a measure of moral disengagement were randomly assigned to play one of the Grand Theft Auto (GTA) violent video games, or a nonviolent game. Self-control was measured using the weight of uneaten chocolates (i.e., M&M’s) in a bowl by the computer. After gameplay, participants could cheat on a test to win raffle tickets for attractive prizes (e.g., iPad). Aggression was measured using a competitive task in which participants could give an ostensible partner unpleasant noise blasts through headphones. Results showed that violent video games decreased self-control and increased cheating and aggression, especially for people high in moral disengagement.