The article profiles an in-service programme used to introduce a group of 22 high school mathematics teachers to an ethno-mathematical approach. The programme was built on an ongoing district-wide teacher development initiative organized and facilitated by the mathematics district official on a monthly basis. The programme took place over six months and consisted of three workshops, monthly cluster meetings and classroom visits. All the activities were carried out by various mathematics education practitioners. The results showed the varying degrees of impact of the in-service programme on the teachers.