This chapter introduces the concept of ecology, which alongside community and performance is one of three theoretical contexts for this book. It sets out some of the ways in which the term “ecology” is understood. First it looks at the basic scientific ecology of ecosystems, observing population-community and process-functional dynamics as defined by Eugene P. Odum. It then considers the political ecology approaches of conservation and preservation, recognising these to be guided by drivers of crisis, cause, and solution. We look at the history of US environmentalism in the work of John Muir, Gifford Pinchot, and Aldo Leopold, before acknowledging first nation understandings of the environment. It then moves on to Arno Naess’s concept of deep ecology, Gregory Bateson and Félix Guattari’s understandings of the ecology of mind, and Timothy Morton’s invocation of dark ecology.