A shekara ta 1848, Engels ya rubuta littafin The Communist Manifesto tare da Marx kuma ya rubuta da kuma rubuta (musamman tare da Marx) wasu ayyukan. Daga baya, Engels ya tallafa wa Marx da kudi, ya ba shi damar yin bincike da kuma rubuta Das Kapital. Bayan mutuwar Marx, Engels ya wallafa kundi na biyu da na uku na Das Kapital. Bugu da ƙari, Engels ya shirya bayanin kula na Marx game da Theories of Surplus Value, wanda ya buga daga baya a matsayin "na huɗu" na Capital.
Engels