Working class (or lower class, labouring class, sometimes proletariat) is a term used in the social sciences and in ordinary conversation to describe those employed in lower tier jobs (as measured by skill, education and lower incomes), often extending to those in unemployment or otherwise possessing below-average incomes. Working classes are mainly found in industrialized economies and in urban areas of non-industrialized economies.

As with many terms describing social class, working class is defined and used in many different ways. When used non-academically, it typically refers to a section of society dependent on physical labor, especially when compensated with an hourly wage. Its use in academic discourse is contentious, especially following the decline of manual labor in postindustrial societies. It is often used synonymously for proletariat, particularly amongst Marxist authors. Some academics question the usefulness of the concept of a working class.

The term is usually contrasted with the upper class and middle class, in general terms of access to economic resources, education, cultural interests, and other goods and services. The cut-off between working class and middle class is more specifically where a population spends money primarily as a lifestyle rather than for sustenance (for example, on fashion versus merely nutrition and shelter). Problematically, relying on this method of distinction would rule out many of the people who are often identified as working class.