Friedrich Engels' treatise The Condition of the Working Class in England is published in Leipzig as Die Lage der arbeitenden Klasse in England in 1845.

Written during Engels's 1842–44 stay in Manchester, the city at the heart of the Industrial Revolution, it is a compilation of Engels' own observations and detailed contemporary reports.

Engels had shown Marx his book the previous year in Paris, and had persuaded Marx that the working class can be the agent and instrument of the final revolution in history.