This study analyzes legislative voting in the French National Assembly during the Fifth Republic. We use an original data set of roll-call votes to understand the development of party voting unity from the Ist to the XIIIth Legislature (1958-2012). We also include a spatial analysis of legislative voting to measure the dimensionality of politics in the legislature. Our results show that party unity is very high in the National Assembly and that the policy space in the legislature is primarily one-dimensional. However, we note that party unity is weaker under certain circumstances, particularly when voting is related to foreign policy issues and the European Union, or when the government is composed of an ideologically diverse coalition of parties.