Summary This article illuminates the transforming impact of collective action in the light of the industrial jacquerie of 1886 in Belgium. This important episode of popular struggle fuelled a dialectical process of change which was marked by a fundamental shift in both social policy and in repertoires of collective action. In 1886 workers still drew on an old repertoire of collective action. Their struggle had such a disruptive force that it forced the state to intervene in labour conflicts. The conservative political élite responded with conciliatory gestures that foreshadowed a legislative programme of social reform. In the changed political climate the position of progressive wings in the two conservative parties was enhanced as the growing strength of the labour movement became more apparent. The industrial jacquerie functioned as a catalyst in the transition from old to new repertoires of collective action. In the aftermath of the revolt, mass collective action quickly, and extensively, came under the control of the Parti Ouvrier Belge (POB).