We investigate strategic voting in proportional representation (PR) systems where parties are organized in pre-electoral coalitions and subject to a vote threshold. We show that such political systems are likely to generate coordination problems among the supporters of a coalition, and we examine voter behavior in this setting using a laboratory experiment with repeated rounds of elections. Our findings suggest that in absence of electoral history, voters cannot coordinate their efforts successfully and are more likely to vote sincerely. However, as history becomes available, the vote threshold induces strategic coordination on parties that performed best in previous elections.
