A central premise in representative democracy is that people vote for the party or candidate offering the best fit with their policy preferences. While central in studies on general elections, ideological congruence is underexposed in studies on intraparty elections. Our research maps one-to-one congruence between individual party members and their preferred candidate in a party leadership contest, and investigates whether members with high political sophistication and strong party linkage are more likely to cast a congruent vote. The analysis is based on original survey data collected among more than 4,300 party members of two Belgian parties. We find that ideological congruence in leadership elections is rather high, but that members do not always vote for the most congruent candidate. Like in general elections, sophisticated, engaged, and more satisfied voters cast a more congruent vote.