Norwegian party politics is characterized by coalition avoidance that defies conventional coalition theory. This failure of coalescence can be caused either by policy pursuit (preference-induced) or by institutional constraint (structure-induced). We test the explanatory power of policy-based and institutional explanations, relying on content analysis of authoritative party and government documents for our policy measures. The results show that the left–right policy dimension has powerfully constrained Norwegian interparty bargaining and that policy-based coalition theory can account for many apparent anomalies in Norwegian coalition politics. A permissive institutional environment has also fostered coalition avoidance. Although core-based coalition theory can thus be successfully adapted to the Norwegian case, it rests on a number of critical assumptions that limit its general applicability.
