This paper reports on a school-based intervention in which a family therapist, serving as a consultant to a high school, worked with that school to reduce the level of school-based violence. The primary intervention reported in this paper is a conflict skills training programme called ‘Making the Smart Choice’. While designed for the families of students suspended for physical violence, this intervention also impacts upon the school's disciplinary system and the climate of the school itself. The context or responses to school-based violence, the strategy to gain access to the school, the politics of developing such a programme, the programme itself and the infrastructure needed to maintain it are described. For four years, suspensions for school-based violence were halved compared to the four years prior to the start of the programme.