For the second time in the history of the French Vth Republic, thefirst having led to the resignation of Charles De Gaulle in 1969, apresident lost a national referendum. On May 29, 2005, 54.7% ofFrench voters rejected the European Constitutional Treaty, eventhough France was one of the major proponents of the EuropeanConvention which led to the Constitution's drafting. The victory ofthe “no” vote had been foreseen, but neither the margin of victory,nor the high turnout (almost 70.5%) were expected. The rejection ofthe Constitution raised two concerns: the first related to theposition of France in Europe, the second to its domestic impact. Whydid the French electorate vote as it did? Did voters make up theirminds based on national cues, the European issue being generally oflittle importance even in European elections (Franklin, Marsh, and McLaren 1994; Van der Eijk and Franklin 1996)? Is the referendumresult the consequence of a growing anti-European attitude, whichcould cause considerable damage to the process of EU integration?Will a new cleavage grounded on attitudes to Europe and capable ofaltering the traditional left-right organization emerge in theFrench political system?Our warmestthanks to our colleagues, Chantal Barry, Arianne Chebeld'Appolonia, and Manlio Cinnalli for their remarks on and theirhelp with this piece.