This paper examines how a party’s decision to enter a coalition government affects voter perceptions of the party’s policy position. We argue that, for the decision to change voter beliefs, it must be at odds with voters’ prior opinions about the party. Specifically, the party must join a coalition that is not the one voters perceive as the ideologically closest option. Otherwise, the party’s action simply confirms voters’ pre-existing beliefs. Hence, whether or not joining a coalition alters voter attitudes depends on the type of alternative coalitions the party could enter. We test the hypothesis using three complementary empirical strategies: a cross-country analysis of party reputations in five coalition-prone European countries, individual panel data, and a quasi-experimental test. All three empirical tests provide support for our claim. This paper contributes to our understanding of voter information processing, coalition politics, and party competition.