Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Although teachers are key figures of a program’s effectiveness, most intervention studies to date have not explored how anti-bullying programs are associated with changes at teacher level. Moreover, teacher data also informs about aspects of program implementation, which are essential in program evaluations. Therefore, the aim of this study was to gain insight into the perspectives of teachers working with the Olweus Bullying Prevention Program (OBPP). A scientific evaluation of the OBPP was carried out in 21 German schools. In addition to annual student surveys, regular teacher surveys were conducted. Ordered logistic regressions and linear regressions were used to estimate the variables. As we expected a dosage-response effect, we divided the schools by level of implementation (non-completer, completer, and certified Olweus schools). At baseline, 615 teachers took part in the assessment (68.26%), and 388 teachers at postline 2 years later (47.32%). A positive change in teachers’ intention to intervene in bullying could be found across all schools (<jats:italic>p</jats:italic> < .001), which was only significant for completer (<jats:italic>p</jats:italic> < .001) and certified schools (<jats:italic>p</jats:italic> = .004) when differentiated by implementation level. Teachers’ level of job strain did not change at all (non-significant model fit), while an improvement in school climate only emerged for certified schools (<jats:italic>p</jats:italic> = .003). The moderating effect of the implementation level turned out to be independent of different school characteristics. The self-reported changes at the teacher level depended on the level of program implementation. Therefore, it is essential to record data about the intensity of program activities when evaluating a program.</jats:p><jats:p>Trial registration number: DRKS00008202 (date of registration: 08/04/2015).</jats:p>