In French election studies, a central debate concerns the French voter's ‘standing decision’ – is it party or ideology? The debate has been ongoing because of data and measurement issues and, we add, because of an inadequate understanding of the role electoral institutions play. The 1995 French National Election Study allows a fresh attack on these questions. It contains promising party and ideology measures, on a very large national sample. Both party identification and left–right ideological identification are shown to be widely held, with the latter more so. Their relative structural effects are found to depend heavily on the dynamics of the dual ballot. Party is more important for electoral choice on the first ballot, while ideology is more important on the second. This finding, demonstrated in fully specified logistic regression models of the presidential vote, seems also to inhere in the logic of French electoral institutions. The two-ballot rules, coupled with the pervasiveness of ideological and party identification in the public mind, go far towards revealing and explaining an underlying stability of the French political system.