Class composition analysis came together in the 1960s as part of an Italian Marxist intellectual movement known as Operaismo (Workerism). It has been in continual use and development since then. It is useful because it understands class not as a thing, not as something given or pre-existent, but rather as something that happens. Class gets composed, decomposed and recomposed on a continual basis as both capital and the working-class struggle to assert their opposed interests. As class composition changes, then the most effective ways of organising and struggling also change. It’s a tool to promote tactical and strategic innovation. Many of the ideas and practices that Plan C has worked on, such as the Social Strike, Social Reproduction and the Women’s Strike, are informed, to one extent or another, by class composition analysis. This workshop will provide a beginner’s guide to the history and practice of this form of analysis and how we can use it today.