OBJECTIVE: One of the most widely used evidence-based anti-bullying programs, KiVa, originates from Finland and aims to change students\' peer context, activate teachers, and inform parents with two main components (universal preventive actions and indicated actions when bullying occurs), complemented by monitoring. Because research documented somewhat varied KiVa outcomes in different countries and because there is a lack of research focusing solely on the effectiveness of the universal and indicated actions, this study aimed to evaluate the effectiveness of KiVa main components when implemented in a new country. This two-arm parallel cluster randomized control trial (RCT) evaluated the effectiveness of the KiVa anti-bullying program in elementary schools in the Czech Republic. It examined the effects of the universal and indicated actions on self-reported bullying and victimization as primary outcomes and well-being as a secondary outcome, while keeping monitoring constant across the intervention and control schools. The study also examined the role of implementation fidelity on the proposed outcomes.
METHODS: Schools were allocated via stratified randomization into a KiVa intervention group (12 schools, 35 classes, N = 407 students) or a wait-list control group (12 schools, 32 classes, N = 400 students). The study employed data from baseline and post-measurement waves, which were 10 months apart.
RESULTS: The data were analyzed using linear mixed effects models, which showed no significant intervention or fidelity effects for bullying, victimization, and well-being. However, promising trends (at α < .10) were revealed, such as lower levels of bullying observed in the intervention group and in schools with high implementation fidelity. Additional analysis using Bayes factors supported these promising trends and provided moderate support for lower levels of victimization in the intervention group compared to the control schools.
CONCLUSIONS: Evaluation of effectiveness of anti-bullying programs could benefit from a more targeted fidelity assessment at the classroom or individual level and from distinguishing between the effects of the main components of the programs and the effects of monitoring. The promising yet non-significant intervention and fidelity effects suggest that schools may require enhanced support and longer implementation time frames than a single school year, especially when implementation faces structural obstacles, such as the Covid-19 pandemic.

Bullying victimisation is a serious risk factor for mental health problems in children and adolescents. School bullying prevention programs have consistently produced small to moderate reductions in victimisation and perpetration. However, these programs do not necessarily help all students affected by bullying. Paradoxically whole-school programs lead to higher levels of depression and poorer self-esteem for students who continue to be victimised after program implementation. This may be because some elements of whole-school programs make victims more visible to their peers, thus further eroding their peer social status. Three main identified risk factors for children and adolescents who continue to be victimised following school bullying prevention programs are peer rejection, internalising problems, and lower quality parent-child relationships. All are potentially modifiable through family interventions. A large body of research demonstrates the influence of families on children\'s social skills, peer relationships and emotional regulation. This paper describes the theoretical foundations and empirical evidence for reducing the incidence and mental health outcomes of school bullying victimisation through family interventions. Family interventions should be available to complement school efforts to reduce bullying and improve the mental health of young people.

Bullying behavior is a concern among school-aged youth and anti-bullying programs have been implemented in schools throughout North America. Most anti-bullying programs are delivered to adolescent youth because antisocial-aggressive behaviors are typically associated with this developmental stage. This paper is a review of empirically evaluated school-based bullying prevention and intervention programs in North American elementary schools.
We conducted a systematic, critical review of bullying prevention programming. Data were analyzed to determine the study method, intervention components, measurement of bullying, aggression, or peer victimization, outcomes measured, and results.
Our review resulted in the identification of 10 interventions aimed at youth in grades K-6 enrolled in North American elementary schools. Effective intervention strategies targeted a variety of bullying behaviors using diverse mechanisms and included a school-and community-wide approach. Direct outcomes of the reviewed evaluations were centered on bullying, aggression, and victimization. Indirect outcomes of review evaluations included strategies for bystanders, school achievement, perceived school safety, and knowledge or attitudes about bullying.
Recommendations for promising practices in effective bullying intervention programming are offered. The review concludes with suggestions for supporting school health staff and in-service teachers drawn from the body of research, and offers direction for future study.

The purpose of this quasi-experimental study was to evaluate a large-scale implementation of the Olweus Bullying Prevention Program with children and youth in grades 3-11 in the U.S. Two major sets of analyses are presented, one following 210 schools over two years (Study 1; n = 70,998 at baseline) and the other following a subsample of 95 schools over three years (Study 2; n = 31,675 at baseline). Schools were located in 49 counties in central and western Pennsylvania. The Mplus 7.0 program was used to analyze the data which had a multilevel structure, with students nested in schools and program effects based on school-aggregated outcome variables. For almost all grades, there were clear reductions in the two key dimensions, being bullied and bullying other students. Average Absolute Change amounted to approximately 3%, implying that almost 2000 students had escaped being bullied in the two-year study. School-level Cohen\'s d\'s were large or fairly large. The longitudinal analyses documented increases in students\' expressions of empathy with bullied peers, marked decreases in their willingness to join in bullying, and perceptions that their primary teacher had increased his or her efforts to address bullying. Overall, effects were stronger the longer the program had been in place. The analyses provided strong support for the effectiveness of the OBPP with U.S. students in elementary, middle, and early high school grades in Pennsylvania schools. Future research is warranted to assess program effectiveness in different racial/ethnic and community settings and to examine the relation between fidelity of implementation and outcomes.