Many studies have shown that media violence has an effect on children's subsequent aggression. This study expands upon previous research in three directions: (1) by examining several subtypes of aggression (verbal, relational, and physical), (2) by measuring media violence exposure (MVE) across three types of media, and (3) by measuring MVE and aggressive/prosocial behaviors at two points in time during the school year. In this study, 430 3rd-5th grade children, their peers, and their teachers were surveyed. Children's consumption of media violence early in the school year predicted higher verbally aggressive behavior, higher relationally aggressive behavior, higher physically aggressive behavior, and less prosocial behavior later in the school year. Additionally, these effects were mediated by hostile attribution bias. The findings are interpreted within the theoretical framework of the General Aggression Model. Aggr. Behav. 37:193-206, 2011. (C) 2010 Wiley-Liss, Inc.