This dissertation investigates the ways in which contemporary composers engage with nature through music. Through three case studies of compositions by Hildegard Westerkamp, John Luther Adams, and myself, I highlight a toolbox of biocentric composition techniques: techniques for meaningfully incorporating the natural world into music without exploiting it. In the process, I help to define the varied and ever-growing field of biocentric music—a new phrase I have coined to refer to the longstanding tradition of music based in mutual relationships between humans and nature. The three case studies represent a variety of different approaches to biocentric composition in the twentieth and twenty-first centuries, many of which involve the use of new technology. I argue that biocentric music is distinguished from other music that deals with nature by its relationality: composers must prioritize building a relationship with their environments as part of the creative process. Without this connection, composers run the risk of harvesting their sonic materials in a way that is analogous to the extraction of other natural resources: for their own benefit and that of their listeners, without consideration for the environment in all its complexities and varied life-forms. / Music Composition / Accompanied by one .pdf file : 1) Selin_temple_0225E_171/HSelin_compiled_graphicanalysis_becomeocean.pdf