Political parties use policy radicalism as a means of attaining electoral success. Differentiation from other parties and ideological renewal after a period of incumbency or prolonged opposition are valid reasons for policy innovation, but excessive radicalization has a number of detrimental effects, including mismanaging voter expectations. This article analyzes a number of examples of policy radicalization under the French Fifth Republic. It starts from concepts taken from policy mood and spatial competition models, and examines how French political parties of both Left and Right have overreached in their ideological stances, and thereby exacerbated political disenchantment among the French public. The article concludes by looking at the notion that mainstream politicians may not be acting in their own best interests when they radicalize the political agenda by misreading electoral competitive cues.