The following article aims to provide a conceptually rooted introduction to the articles in the internationally coordinated themed collection on Labour Conflict, Class and Collective Organization, an initiative which has involved four journals focusing on labour studies from different geographical angles and academic traditions: Economic and Labour Relations Review (ELRR); Global Labour Journal The contributions across the four journals are diverse, both in terms of geographical focus, disciplinary perspectives and sector of analysis. This diversity is very welcomed and represents a fertile soil for conceptual considerations, because it corresponds to the manifold forms in which labour conflict expresses itself in the reality of capitalism. What's the abstract unity of these concrete empirical realities, as Marx would have put it? In the following introduction, we focus on two general theoretical issues we consider fundamental and mutually interrelated: a rethinking of workers' collective forms of organization within and beyond trade unions; and the framing of these forms and of labour conflict in the broader historical dynamics of working classes formation. With this, we hope to provide a lens of analysis for the articles in the international special issue and, more generally, methodological guidance to future studies on labour conflict.