In this study I present a new understanding of Vietnamese existentialism during the period 1954-1975, the period between the Geneva Accords and the fall of Saigon in 1975. The prevailing view within Vietnam sees Vietnamese existentialism during this period as a morally bankrupt philosophy that is a mere imitation of European versions of existentialism. I argue to the contrary that while Vietnamese existential philosophy and European existentialism share some themes, Vietnamese existentialism during this period is rooted in the particularities of Vietnamese traditional culture and social structures and in the lived experience of Vietnamese people over Vietnam's 1000-year history of occupation and oppression by foreign forces. I also argue that Vietnamese existentialism is a profoundly moral philosophy, committed to justice in the social and political spheres. Heavily influenced by Vietnamese Buddhism, Vietnamese existential philosophy, I argue, places emphasis on the concept of a non-substantial, relational, and social self and a harmonious and constitutive relation between the self and other. The Vietnamese philosophers argue that oppressions of the mind must be liberated and that social structures that result in violence must be changed. Consistent with these ends Vietnamese existentialism proposes a multi-perspective ontology, a dialectical view of human thought, and a method of meditation that releases the mind to be able to understand both the nature of reality as it is and the means to live a moral, politically engaged life. This study incorporates Vietnamese existential philosophy from 1954-1975 into the flow of the Vietnamese philosophical tradition while also acknowledging its relevance to contemporary Vietnam. In particular, this interpretation of Vietnamese existentialism helps us to understand the philosophical basis of movements in Vietnam to bring about social revolution, to destroy forms of social violence, to reduce poverty, and to foster equality, freedom, and democracy for every member of society. By offering a comparison between Vietnamese existential thinkers and Western existentialists, the study bridges Vietnamese and the western traditions while respecting their diversity. In these ways I hope to show that Vietnamese existentialism makes an original contribution to philosophical thought and must be placed on the map of world philosophies. / Philosophy