Abstract: | In most parliamentary democracies, governments must maintain the confidence of a single legislative chamber only. But in bicameral parliaments, upper chambers can affect the fortunes of government policy proposals. Recent work shows that parliamentary governments that lack control over the upper house also tend to collapse sooner than those with upper‐house majorities. In this article, we show that coalition builders anticipate the importance of upper‐chamber status (majority or minority) in making their formation decisions. After controlling for a host of “usual suspect” variables concerning the institutional, ideological, and partisan context of coalition building, and examining 15,590 potential governments in 129 bargaining situations, we found that potential coalitions that control upper‐house majorities are significantly more likely to form than are those with upper‐house minorities. Our findings are important for students of bicameralism, government formation, institutions, and, perhaps most significantly, for those who study policymaking in parliamentary democracies. |