This paper argues that the environmental concerns of Engels were central in the development of his notion of materialism and that his materialist critique of industrial capitalism can be considered as the birth point of the environmental movement. Engels’ environmental masterpiece, “The Condition of the Working Class in England (1844)”, contains an early critique of Malthus as well as the development of the notion of the reserve army of the unemployed. Engels’ work is also a striking portrait of the conditions of the working class in the industrial towns of England. Engels provided a walking tour of the environmental conditions in the manufacturing establishments and slums of the factory towns of England, addressed conditions of widespread pollution focusing especially on environmental toxins and public health conditions, and the impact that these had on workers — including air pollution, lead poisoning, skeletal deformities resulting from malnutrition, and diseases spread by unsanitary water. For Engels, “The Condition of the Working Class in England” was to be the first of a series of connected analyses of ecology that stretched through more than half a century and included his seminal and much disputed work “The Dialectics of Nature”. Here, he argues for the necessity of a materialist conception of nature, insisting on a dialectical approach to materialism, as opposed to mechanical (or mechanistic) materialism. These works make him one of the most important but underappreciated contributors to the development of environmental thought.