John Cage’s Concerto for Prepared Piano and Chamber Orchestra (1950-51) holds a unique position within the composer’s oeuvre as the first work based in part on chance-derived compositional procedures. Cage entered into such practice gradually, incrementally abandoning subjective taste and personal expression through the course of the work. Drawing from the philosophical framework provided by Cage’s "Lecture on Nothing" (1950) and "Lecture on Something" (c. 1951-52), this thesis explores the aesthetic foundations of the concerto and examines Cage’s compositional methodology throughout its three movements. Special attention is paid to the procedure underlying the first movement, whose analysis is based largely on the composer’s manuscript materials for the work.