Theory and research on media violence provides evidence that aggressive youth seek out media violence and that media violence prospectively predicts aggression in youth. The authors argue that both relationships, when modeled over time, should be mutually reinforcing, in what they call a downward spiral model. This study uses multilevel modeling to examine individual growth curves in aggressiveness and violent media use. The measure of use of media violence included viewing action films, playing violent computer and video games, and visiting violence-oriented Internet sites by students from 20 middle schools in 10 different regions in the United States. The findings appear largely consistent with the proposed model. In particular, concurrent effects of aggressiveness on violent-media use and concurrent and lagged effects of violent media use on aggressiveness were found. The implications of this model for theorizing about media effects on youth, and for bridging active audience with media effects perspectives, are discussed.