We analyze two-candidate elections in which some voters are uncertain about the realization of a state variable that affects the utility of all voters. We demonstrate the existence of a swing voter's curse: less informed indifferent voters strictly prefer to abstain rather than vote for either candidate even when voting is costless. The swing voter's curse leads to the equilibrium result that a substantial fraction of the electorate will abstain even though all abstainers strictly prefer voting for one candidate over voting for another.

We analyze two-candidate elections in which voters are uncertain about the realization of a state variable that affects the utility of all voters. Each voter has noisy private information about the state variable. We show that the fraction of voters whose vote depends on their private information goes to zero as the size of the electorate goes to infinity. Nevertheless, elections fully aggregate information in the sense that the chosen candidate would not change if all private information were common knowledge. Equilibrium voting behavior is to a large extent determined by the electoral rule, i.e., if a candidate is required to get at least x percent of the vote in order to win the election, then in equilibrium this candidate gets very close to x percent of the vote with probability close to one. Finally, if the distribution from which preferences are drawn is uncertain, then elections will generally not satisfy full information equivalence and the fraction of voters who take informative action does not converge to zero.

We analyze a model of participation in elections in which voting is costly and no vote is pivotal. Ethical agents are motivated to participate when they determine that agents of their type are obligated to do so. Unlike previous duty-based models of participation, in our model an ethical agent's obligation to vote is determined endogenously as a function of the behavior of other agents. Our model predicts high turnout and comparative statics that are consistent with strategic behavior.