Through the nineteenth century, Western industrial nations transitioned to fossil fuels following the formation of what Andreas Malm terms “Fossil Capital,” a distinct form of capitalism based on the extraction and consumption of coal, oil, and gas. In America, the industrial operations of fossil capital – in addition to igniting our contemporary climate crisis – reshaped society in the image of a productive engine through social interpretations of the thermodynamic principles of energy conservation and entropy. Through readings of key naturalist texts from the period when fossil capital firmly established itself as America’s dominant socioeconomic form, this thesis considers American literary naturalism as an aesthetic response to the reordering of the nation’s society around the consumption of fossil fuels. It argues that Fredric Jameson’s understanding of naturalism as a narrative mode that communicates class anxieties through an “entropic trajectory” invites a thermodynamic reading that foregrounds the literary form’s relationship to fossil capital’s socioeconomic and environmental transformations. Each chapter examines the ways in which a pair of American naturalist novels engage in or resist a tendency to imagine the developments of fossil capital as manifestations of thermodynamic laws. In doing so, this thesis presents a reconsideration of American literary naturalism that highlights the form’s ideological function in the establishment of a fossil-fuelled industrial middle class fixated on productivity. The form’s ideology, it demonstrates, ultimately works to present the rise of fossil capital as a natural – and, as such, immutable – phenomenon.