When we watch violent movies and play violent videogames, we necessarily entertain violence, which is to say we think about it and imagine it. Brain science shows that when we imagine an action or situation, we rehearse it in those parts of the brain involved in similar situations in the real world. We do not merely observe and judge violence that we see on the screen, in other words; we are actively involved in it, even if only imaginarily. There is no question that this kind of involvement has physiological, psycho logical, behavioral, and cultural effects. Since real world violence is harmful, it behooves us to weigh carefully what these effects are. Yet we should be careful about jumping to conclusions.