This dissertation research project investigates the role that science and technology played in shaping the built and natural environments of Seattle, Washington between 1880 and 1970. It is designed to cast historical light on the creation, growth, and development of urban ecosystems. It will also suggest how the reciprocal influences between science, technology, society and culture shape human understandings of the natural world. It brings environmental history and science and technology studies together by investigating how the built and natural environment together comprise Seattle. The project hopes to demonstrate that urban environmental concerns flow from historical conditions that fused the built with the natural. More specifically, `Working Nature` charts how engineers, city planners, workers, and political leaders created the infrastructure and urban forms integral to Seattle's growth. The research focuses on how material changes to Seattle's landscapes both reflected and affected how citizens used and understood nature. Scientific ideas and technological systems employed to create Seattle's urban environment mediated changes in the land. They also played no small role in determining how residents would come to identify their city as close to nature, and what shape future plans for Seattle would take. Phase one of the research focuses on the local primary source material for the period between 1880 and 1940. It will also look at records associated with Seattle's railroad development and park design housed in Minnesota, Massachusetts, and Washington, D.C. Phase two returns to local sources, this time after World War II, to examine how changing attitudes toward city nature influenced attempts at environmental management in the face of previous landscape changes.