Academics and political practitioners alike have long concerned themselves with the representativeness of primary electorates. Hoping to moderate the ideological extremity of primary voters, state parties have increasingly adopted more open primary eligibility rules. This article explores the extent to which open and modified-open primaries actually attract a more representative electorate than their closed counterparts. Using state-level exit poll data from 1988 through 2000, we compare the ideological, age, and income representation of primary electorates with general election voters. We find that open primaries result in the ideological convergence of the parties’ primary electorates, although the extent of this convergence is contingent upon the candidate choices within individual election years. Notably, open primaries are responsible for the inclusion of younger participants in both parties’ primaries. While reformed primary structure may weaken party control over the nomination process, it clearly results in more moderate and more representative primary electorates.