This thesis examines the phenomenology and significance of agoraphobia for its mostly women sufferers, principally by means of in-depth individual and group interviews. It argues that agoraphobia, typically characterised by fear and avoidance of social spaces, can be usefully conceptualised in terms of a 'crisis' in the boundaries of the embodied self. That is to say, the disorder radically problematizes the distinction individuals 'normally' experience between 'inner' self and 'outer' space, initiating a profound sense of exposure and insecurity in the face of many social situations. In response, sufferers retreat from the social sphere to the seclusion of their homes, whose walls serve to reinforce their weakened and fragile boundaries. The initial impetus behind this project stems from the fact that, while there has been no shortage of clinical research conducted on agoraphobia, it has received very little attention outside bio-medical and psychological contexts. Chapter l reviews relevant bodies of literature and highlights some of the gaps the project seeks to address. Chapter 2 offers a detailed account of the research design, and the ways in which data were generated and analysed, while chapter 3 offers reflections on what was found to be the 'processual' nature of qualitative research. In each of the five substantive chapters that remain, the thesis interweaves experiential accounts with existential problematics, and presents a general movement from concerns with theory to therapy. It also follows the unfolding development of the existential and phenomenological tradition. Chapter 4 links the more esoteric and subjectivist existentialism of Kierkegaard with experiential accounts of consumption, and chapter 5 explores the socially grounded work of Sartre in relation to sufferers' accounts of extreme discomfort in the public eye. Chapters 6 and 7 utilise the explicitly spatial, embodied, and inter-subjective account of existentialism presented by Merleau-Ponty to present first, a case study, and second, an analysis of sufferers' accounts of pregnancy. In this way the thesis ii also moves from abstract philosophical arguments about the human condition per se to a more nuanced feminist geography capable of accounting for the diversity of experiences of agoraphobia and its gendered relations to pa11icular times and places. In its final chapter, the thesis turns to an explicit discussion of treatment, and critiques the unacknowledged predominance of and reliance on masculinist Cartesian conceptions of selfhood within self-help resources, questioning what treatment based on models of embodied subjectivity more inclusive of unusual spatial relations might look like. In its conclusion, the thesis suggests that by taking account of personal narratives of agoraphobia, and of its wider social contexts and relations, a sensitive, sympathetic and fully spatialised account of the disorder more faithful to the way sufferers actually describe their experiences can be offered.