Background: Despite the existing national and international plans of action to end violent discipline strategies used by teachers in schools, they still prevail in Tanzanian schools. This underlines the need to implement schoolbased interventions that aim at reducing violent discipline by teachers. In this study, we will evaluate the feasibility and effectiveness of the preventative intervention Interaction Competencies with Childrenfor Teachers (ICC-T) in Tanzanian primary schools. Following its success in secondary schools, we hypothesize that the intervention will reduce teachers' positive attitudes towards and their use of violent discipline at school.Methods/design: The study will be conducted in six randomly selected regions in Tanzania. We have already randomly selected two schools in each region (12 in total) that fulfill our inclusion criteria. From each region, one school will be randomly assigned to the intervention and the other to the monitoring group (no intervention). Eighty students between the ages of 9 to 12 years (N = 960) and 20 teachers from each school (N = 240) will be included in the trial. We will collect data directly before the intervention (t1) and 6 months after the intervention (t2) both at intervention and monitoring schools. Using guided questionnaire assessments, we will measure violence by teachers using students' reports on their exposure to and teachers' reports on their use of violence using the Conflict Tactics Scale. Furthermore, we will assess teachers' positive attitudes towards violent discipline using a modified version of the Conflict Tactic Scale. The feasibility of the intervention will be evaluated using purpose-built measures assessing the demand, applicability, acceptability, and integration of core elements into daily work in the participating schools. Discussion: The proposed study will allow us to test the feasibility and effectiveness of an intervention aiming to reduce positive attitudes towards and the use of violent discipline by teachers in school settings. With the reduction of violent discipline by teachers, this study contributes to national and international efforts towards ending violence against children as well as the attainment of the United Nations' Sustainable Development Goals that also aim to prevent all types of maltreatment of children.