Research Basis for the Olweus Bullying Prevention Program

 The effectiveness of the Olweus Bullying Prevention Program has been assessed in several studies in Norway and in the United States.

Studies in Norway

First Bergen Project

The first evaluation of the program took place in Bergen, Norway and targeted 2,500 children in grades 5-8 over a period of 2½ years between 1983 and 1985.  Findings revealed:

  • Substantial reductions (50% or more for most comparisons by students’ age and grade) in self-reported bullying and victimization.
  • Significant reductions in self-reported vandalism, fighting, theft, alcohol use, and truancy.
  • Reductions in teachers’ and students’ ratings of bullying among students in the classroom.
  • Significant improvements in the social climate of the classroom (as reflected in students’ reports of increased satisfaction with school life and school work, improved order and discipline at school, and more positive social relationships).
  • Fidelity of program implementation was related to program outcomes--those classrooms that implemented essential components of the program saw greater reductions in bullying problems.

Follow-up Studies in Norway

Six follow-up evaluations of the OBPP have taken place in Norway, involving more than 20,000 students from more than 150 schools. Findings from students in grades 4-7 revealed consistently positive program effects.

Studies in the U.S.

Several studies have evaluated the effectiveness of the OBPP in diverse settings within the United States.

South Carolina

The first evaluation of the OBPP in the U.S. involved students in elementary and middle schools in SC in the mid-1990s.  After one year of implementation, and compared with schools not implementing the OBPP, researchers found:

  • Large, significant decreases in boys’ and girls’ reports of bullying others.
  • Significant differences between intervention and comparison schools in self-reports of delinquency, vandalism, school misbehavior, and sanctions for school misbehavior.

Philadelphia, PA

An evaluation of the Olweus program in 12 elementary schools in the Philadelphia area found significant reductions in observations of bullying at recess and lunch.

Commonwealth of PA

Researchers have recently conducted the largest evaluation of the OBPP to date in the U.S.  Analyses included more than 72,000 students at baseline assessment in grades 3-11 from 214 schools.  Findings revealed:

  • Positive effects of the OBPP on student reports of being bullied and bullying others.
  • Program effects were larger the longer the program had been in place.

Summary of PA findings presented at the International Bullying Prevention Association, 2013.


Recent meta-analyses by Ttofi & Farrington revealed that bullying prevention programs are effective in reducing bullying.  These authors noted that those programs “inspired by the work of Dan Olweus worked best” (Ttofi et al., 2008, p. 69).

Research Summary & References



© 2003-2018 Olweus Bullying Prevention Program