However, social stimuli such as media violence can produce different effects in laboratory as compared to nonlaboratory settings. Thus, research in laboratory settings may not provide accurate information about the effects of media violence in nonlaboratory settings. Some types of quasi-experimental field research can provide evidence about the long-term socialization and developmental effects of media violence on viewer's behavior in naturalistic settings. The present article summarizes the findings from a number of quasi-experimental studies about the effects of naturally occurring media violence. It concludes that the balance of the findings are consistent with the hypothesis that television produces a long-term increase in the aggressive behavior of boys but not of girls. (Author abstract)