Frederick Engels’s Anti-Dühring was the most important theoretical response to the emerging reformist tendencies within European socialism in the 19th century. It also proved to be Engels’s most influential, and controversial work. Because it is, as Hal Draper points out, ‘the only more or less systematic presentation of Marxism’ by either by Marx or Engels, anyone wanting to reinterpret Marx must first detach it from his seal of approval. It is thus around Anti-Dühring and related texts that debates about the relationship of Marx to ‘Engelsian’ Marxism have tended to focus. This essay re-engages with debates about Engels’s mature work with a view to unpicking his contribution to Marxism from caricatured criticisms of his thought.