KiVa antibullying program is the most widely used and most thoroughly researched bullying prevention program in the world. It has been found to be feasible, possible to roll-out in a large scale (even nationwide in Finland), sustainable, effective, and cost-effective. The effects have been found in several randomized controlled trials, both in Finland and in other countries. After the wide roll-out of the program in Finland in 2009, the prevalence of students bullying others and those bullied by others have been decreasing steadily, according to several independent large-scale surveys.
