Political parties can be seen as agents of both integration and division. Attachment to political parties may function as an integrating mechanism by channeling political and ideological polarization away from system-challenging activities towards the regime support and acceptance of the prevailing political (democratic) order. At the same time, parties might also foster extremism and dissatisfaction with democratic performance. This paper examines these possibilities using Dutch Election Studies data. The empirical examination of the relationships between the triangle of ideological extremism, partisanship, and satisfaction with democracy provides mixed support for both interpretations, and emphasizes the double role of partisanship.