How do voters make decisions about who to vote for in presidential elections, especially when they are poorly informed about candidates and the issues? R. Michael Alvarez, in this groundbreaking study, shows that a tremendous amount of information has been made available to voters in recent elections and that voters do learn about candidates during presidential campaigns. Alvarez begins with the assumption that voters do not have the incentive nor the inclination to be well informed about politics and presidential candidates. Also, candidates themselves have incentives to provide ambiguous information about themselves, their records, and their issue positions. And yet Alvarez shows that a tremendous amount of information is made available about presidential candidates. He uncovers clear and striking evidence that voters penalize ambiguous candidates; moreover, voters are unlikely to vote for candidates about whom they know very little. Alvarez explores how voters learn about candidates through the course of a campaign. He uses a rational choice framework to show how imperfect information affects the decisions voters make about presidential candidates.