Parliamentary elections to the Basque Autonomous Community have a stable multi-party system that regularly produces long-lived minority and coalition governments. More amazing still, this stable party system arises in the context of a complex social and political setting in which the society cleaves along at least two lines – ideology and nationalism – and in which people have strong identities tied to the Basque language and culture. This paper analyzes voting behavior in parliamentary elections in this region to understand how ideology, nationalism, and identity sustain this party system. We extend the conventional spatial voting model to incorporate identity issues. Our empirical analysis shows that ideology, nationalism (or regional autonomy) and identity strongly predict vote choice, and, surprisingly, that ideology is much more salient in vote choice than nationalism.  Interestingly, the analysis suggests that that identity politics both polarizes voting and sustains a stable multi-party system.