Understanding citizens' electoral behavior (e.g., selective abstention and split ticket voting), represents a fundamental step in the analysis of democratic institutions. In this paper, we assess the extent to which sincere voting can explain observed patterns of participation and voting in U.S. national elections. We propose a unified model of turnout and voting in presidential and congressional elections with heterogeneous voters. We estimate the model using individual level data for eight presidential election years (1972-2000). Our main findings can be summarized as follows. First, a non-negligible fraction of the American electorate does not vote sincerely, and only a relatively small fraction of observed split-ticket voting can be explained by sincere voting. Second, there is a systematic, positive relationship between information and turnout. Third, the American electorate has become relatively more polarized over time.