Research Basis for the Olweus Bullying Prevention Program

 The OBPP is backed by over 40 years of research and has been recognized as the most extensively studied bullying prevention program of its kind.

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.

South Carolina

The first evaluation of the OBPP in the U.S. involved students in elementary and middle schools in South Carolina 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.

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.

The research was published in August 2018 in the Journal of School Psychology and can be accessed here.

Findings revealed that the OBPP was succcessful in reducing all forms of being bullied and bullying others. Read that study published in the International Journal of Bullying Prevention here.

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.

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.

Long-term effectiveness of the OBPP in Norwegian schools

Published in the Scandinavian Journal of Psychology, this study by Dan Olweus and his Norwegian colleagues Mona Solberg and Kyrre Breivik showed that students in 70 elementary schools that continued to implement the OBPP (as evidenced by continued use the Olweus Bullying Questionnaire) had experienced significantly less bullying two to eight years after launching the OBPP, compared with students in 102 schools that had not continued to implement the OBPP. The creative research design took advantage of the fact that between 2007 and 2010, all students completed a National Pupil Survey, which included a question about bullying victimization.

The percentage of bullied students was much lower in schools that continued to implement the OBPP, compared with the national average or schools that began the OBPP in 2002 or 2003 but did not continue to implement the OBPP.


As can be seen in the graph, the percentage of bullied students was much lower in schools that continued to implement the OBPP (red line), compared with the national average (green line) or schools that began the OBPP in 2002 or 2003 but did not continue to implement the OBPP (blue line).

In fact, the likelihood of being bullied in a non-Olweus school was nearly 40% higher than for students who were in schools that continued to implement the OBPP. Results suggested that schools that continued to implement the OBPP had altered their school culture with regard to addressing and preventing bullying. As the authors noted, “the results of our study emphasize the general importance of schools sticking to a program that can document positive effects and letting it become a part of and pervade the schools’ everyday routines. The findings also support our general view that the OBPP should not be seen as a circumscribed, time-limited “program” but rather as a set of principles, procedures and mechanisms designed to create a safe and humane school environment where bully-victim problems are systematically addressed, handled and prevented.”


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).

The Bullying in US Schools: 2019 Status Report updates the 2013 Status Report (Luxenberg, Limber, and Olweus 2014) and reflects the status of bullying around the United States during the 2015–2019 school years (August 1, 2014, through June 30, 2019).

Research Summary & References



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