This dissertation focuses on kayagŭm shin'gok, newly composed music for the kayagŭm, a Korean 12-stringed long board zither. The work examines the relationship between composition, performance and representation of kayagŭm shin'gok in contemporary South Korea. Practitioners of kayagŭm shin'gok have developed new musical repertoire, instruments, and techniques for this genre since the 1960s. This dissertation is the first treatise in any language on kayagŭm shin'gok which contextualizes the genre within the changing social and cultural conditions that have underpinned musical life in modern South Korea. This study is the first English-language dissertation written by a kayagŭm practitioner who has worked with the major performers and composers of this genre.This dissertation is organized around four categories of kayagŭm shin'gok composition and performance. Those include kayagŭm as a living tradition; the boundaries of musical style in kayagŭm shin'gok; kayagŭm shin'gok as a modern high art form; and the social matrix of kayagŭm shin'gok production. Musical analysis focuses on the compositional style and development of Hwang Byung-ki and Yi Sung-chun, composers who are widely recognized as the most influential composers of this genre. Theoretical issues that are examined include composers and composition in an Asian context, musical change, and the role of music in processes of identity formation.As the kayagŭm represents an authentic Korean sound, the social value of this traditional instrument is highly emphasized and legitimized in South Korea. Thus the discourse of "tradition" lives with practices of kayagŭm in contemporary Korean culture. Modernity in kayagŭm shin'gok is defined as being opposed to the music of the "past." Through kayagŭm shin'gok, the meaning attached to kayagŭm music has been changed from a form of entertainment in the early 20th century to a symbol of the nation. Social networks have been important in keeping kayagŭm shin'gok alive, and are made up of diverse layers of relationships within the cultural system of Korean music: composers and performers; teachers and students; patrons and practitioners. Social values and meanings of kayagŭm shin'gok are constantly being negotiated, reaffirmed, and reinforced by these social actors through the institutions that engage the music