Teachers and their associations have played a key role in education reforms. In Chile, their participation has made it possible to establish principles of democracy and equity, which date back to the beginning of education systems. In this context, associations have been instrumental in promoting teachers' political participation, being an essential agent for negotiating a transformative role in teaching. However, teaching associations are currently experiencing a moment of crisis that has had an impact on the reference that teachers have for politicising their work. A qualitative study of 30 in-depth interviews with teachers who are organised and active in their work in the classroom describes the role of teachers' associations in the politicisation of teaching practice in Chile. The results indicate that teachers acquire knowledge within the framework of their associations, which allows for a different kind of teaching practice. However, attendance at a teachers' association does not guarantee this learning, but rather the commitment of teachers to their peers and the politicisation of a perspective of differences. The challenges of politicising work as a meaningful framework for teacher resistance and activism are discussed.