This article draws on a new dataset of House primary- and general-election outcomes (1956–98) to examine the relationship between primary elections and candidate ideology. We show that, like presidential candidates, congressional candidates face a strategic-positioning dilemma: should they align themselves with their general- or primary-election constituencies? Relative to general-election voters, primary voters favor more ideologically extreme candidates. We show that congressional candidates handle the dilemma by positioning themselves closer to the primary electorate. This article thus supports the idea that primaries pull candidates away from median district preferences.