Candidates anticipate the reactions of voters when they decide whether and how to run. In the literature "high quality" candidates are recognized as selective about when they run. They are more likely to enter races they expect to win, and to refrain from running when the propsects are poor. In this literature a "quality" candidate is one with elected office experience, on the argument that such candidates can wage effective campaigns. In my framework, a high quality candidte is one whose policy positions are aligned with the electorate and whose leadership skills and traits are strong. The evidence shows that when challengers' electoral prospects are good, they are more likely to have strong leadership-valence reputations. Challengers with good prospects are also more likely to be aligned with their districts' ideological preferences.