As an independent-minded minister throughout the Fourth Republic, and a political outsider for the first decade of the Fifth Republic, Francois Mitterrand fundamentally distrusted the discipline and collective responsibility implied by belonging to a traditional party. His refusal to join any of the mainstream parties after the Liberation testified to his independence of spirit, as well as his ambiguity in relation to classification in terms of left and right. Mitterrand's relationship with the UDSR in the Fourth Republic has been outlined in Chapter 1. His distrust of classical political parties carried over into the Fifth Republic. To some extent, this was reflected in the style he adopted as the Socialist Party leader after 1971 and as President of the Republic after 1981. In the present chapter, Mitterrand's leadership will be assessed from the perspective of his complex, uneven and ambivalent relation ship with political parties in the Fifth Republic.