The Fete de l'Etre supreme, celebrated throughout France on the 20 Prairial Year II, (8th June 1794), has been the subject of detailed comment by historians since the Revolution, the overwhelming majority of whom have concentrated on the political importance of the festival in the history of the Jacobin administration and in the career of its instigator, Maximilien Robespierre. The intention of this thesis is to re-examine the cultural evidence for the proposition that the Fete was a major benchmark in the cultural development of revolutionary France by evaluating both its immediate cultural impact and its importance to the development of the culture of the later stages of the Revolution. After a brief overview of how historians viewed the events of 20 Prairial, the thesis will first consider why Robespierre might have felt it necessary to proclaim a quasi-religious system such as the Culte of the Supreme Being at this stage of the Revolution, secondly how the French people reacted to his proposal, and finally how the various elements of the Fete integrated with the culture of the period. It will then examine the celebrations not only in Paris but also in other cities, towns and villages throughout France, as well as investigating the financial problem for central, regional, and local government in having to meet the unforeseen extra expense of this event. After examining the reaction to the Fete throughout France as shown in the work of contemporary commentators, this thesis will attempt to prove that the Fete de l'Etre supreme of 20 Prairial Year II, marked the watershed between the exaggerated simplicity and utilitarianism of the early years of the Revolution and the extravagant, colourful and sensual culture of the Directoire and the Consulat.