Priority Populations

Peer Violence Among Teenagers: Trends in Violence and Threats of Violence in Schools: 1991-2010

A special Child Well-Being Index (CWI) report from Duke University tracks trends over time in percentages and numbers of middle and high school students exposed to four forms of peer-to-peer adolescent violence in schools, specifically: threat without injury; threat with a weapon without injury; intentional injury without a weapon; and injury with a weapon. These four activities represent the most extreme forms of bullying.

National data showing how cyberbullying or other kinds of teasing and tormenting among teenagers has changed over time are not now available. However, 15 years of research on CWI indicate that trends in violence tend to move together. The researchers, therefore, believe that the trends in adolescent violence found in Monitoring the Future (MTF), the annual, federally funded survey of teens which forms the basis of this report, can be used to understand general trends in bullying.


  • Until 2010, more teens in middle and high schools were threatened than actually injured; these trends have now merged so that both threats and injuries occur at the same level.
  • Trends in numbers of middle and high school students exposed to all four forms of violence began to increase in 2002 and 2003, peaked between 2007 and 2008, and began to decrease around 2008 and 2009.
  • The annual numbers of adolescents injured intentionally without a weapon showed the greatest fluctuation. Injury without a weapon increased dramatically from 2003-2007, flattened out in 2008-2009, and declined slightly in 2009-2010.
  • All four forms of violent bullying in schools show evidence of increases in the estimated numbers of middle and high school victims in the early 1990s – prior to the most recent peaks. It has been noted, however, that the 2002-2008 years were a period of increased access to the Internet and other forms of electronic communication and the creation and spread of social networking media.


Areas for Further Research

This report raises key questions and highlights an urgent need for further research to address current issues:

  • What are the triggers that lead to an increase in adolescent violence and/or bullying? Why, for example, did we see an increase in intentional injury without a weapon from 2002 to 2008?
  • How are immigration laws impacting violent behavior among teenagers in schools? Is bullying increasing in states that have intensified the search for and the detention and deportation of undocumented immigrants?
  • Did the events of September 11, 2001 impact bullying and/or violent behavior in schools? Did bullying increase in areas with larger populations of families of Middle Eastern descent after the attacks?

For more information see the Foundation for Child Development Summary of the report. 

Visit the Duke University website for more information.