The thesis investigates the political wing of the Occitan ethnoregionalist movement in the south of France from 1974, a point when it had a comparatively high profile, to 2000, and analyses the reasons for its marginalisation over time. Unlike other ethnoregionalist movements in France, it has been subject to little academic research. A study was made of documentary sources, including the internal bulletins of the political organizations and their published journals, which made possible a micro-level perspective on the movement, and revealed some inaccuracies of interpretation by previous researchers. An overview of the evolution of the political wing is established. An evaluation of the functioning and effectiveness of the organizations, which identifies their internal problems, is followed by an investigation of the external factors which contributed to the marginalisation of the Occitan movement. These include the geographical, historical, demographic and socio-linguistic factors which have differentiated the Occitan movement from other French ethnoregionalist movements, and made mobilization of the target audience difficult. By taking a global view of Occitania, rather than focussing, like previous researchers, on Languedoc, the study highlights the extent to which such factors made the movement's aims for political autonomy for the whole of the territory unrealistic. The relative success of the movement in the mid 1970s resulted from the fact that for a period its aims were congruent with the wave of social movement activity in post-1968 France, but the association was not deep-seated. In the 1980s and 1990s the effects of the decentralization reforms and the growth of the Front National had a negative effect on the movement's mobilizational potential. The issue of leadership, referred to briefly in previous studies, is subjected here to more detailed analysis, and is revealed as a significant factor in the weakness of political Occitanism.