Violence is a major issue facing today's youth -- at home, at school, and in the community. At least one in 12 high school-age students is threatened or injured with a weapon each year. And statistics show that since the early 1990s, the incidence of youth violence has reached unparalleled levels in American society. Some have even called it "an epidemic." And no one can explain why. What are the warning signs? Understanding the reasons for violence and knowing what to look are the first steps toward prevention.