This work addresses collective action in the context of a social movement facing police repression in a democratic country. The movement studied was carried out in a region of southern Chile, had a very high citizen participation and deployed normative and non-normative actions. We aim to understand why people decided to participate and how they came to consider violent action as a legitimate option. We use a mixed methods approach. In a quantitative study we compare participation in normative and nonnormative actions, and find they factor together as part of the same action repertoire, making it possible to speak of a continuum of participation instead of different types. We also replicate key findings of the SIMCA model, with protest participation motivated directly by anger and efficacy, but also by positive emotions. In a qualitative study we found similar results and draw out new data highlighting the relevance of the experience of repression in invoking a need for radical action and creating social cohesion among protestors.