The contribution of Eunice Foote (1819–1888) to early understanding of the relationship between atmospheric gases and climate change has become a focus of interest in the scholarly community and more widely on social media. In this article we offer a detailed interpretation of both her known published papers, focusing particularly on her first and most significant paper of 1856, in which she related changes in the types and amounts of atmospheric gases including carbon dioxide to warming and changes in climate. We trace the derivation of her ideas and explore how she constructed, carried out, and interpreted her experiments.