Abstract: Political scientists and practitioners frequently argue that minority legislative parties depend on supermajority rules for policymaking influence. I assess that claim with a new dataset of state legislative roll call votes on revenue increases, a policy area where states vary in whether they require majority or supermajority votes. Despite strong prior expectations, I do not find strong evidence that there is greater minority party participation when a supermajority vote is required and the majority party does not have enough votes to pass the threshold. Instead, I find that bipartisan policymaking is common under both majority and supermajority rules. Through interviews with state-level policymakers, I find that bipartisanship is desired by majority and minority party members for a variety of reasons unrelated to institutional decision rules. Supermajority rules are one of many reasons that minority party members participate in policymaking, but they are probably not the most important nor are they a necessary condition for bipartisanship. My research suggests that scholars should look beyond institutional decision rules when assessing the minority party’s role in policymaking.