We study a citizen-candidate-entry model with private information about ideal points. We fully characterize the unique symmetric equilibrium of the entry game and show that only relatively “extreme” citizen types enter the electoral competition as candidates, whereas more “moderate” types never enter. It generally leads to substantial political polarization, even when the electorate is not polarized and citizens understand that they vote for more extreme candidates. We show that polarization increases in the costs of entry and decreases in the benefits from holding office. Moreover, when the number of citizens goes to infinity, only the very most extreme citizens, with ideal points at the boundary of the policy space, become candidates. Finally, our polarization result is robust to changes in the implementation of a default policy if no citizen runs for office and to introducing directional information about candidates’ types that is revealed via parties.