Objective This article investigates the role of income and income heterogeneity on voters’ preferences for the conservative party. Methods Fitting a series of logistic regressions on exit poll data from the 2006 and 2012 Mexican presidential elections. Results We find that heterogeneity mediates the effect of income on the probability of voting for the conservative candidate. Conclusion In more heterogeneous places, rich voters are more likely to support the candidate on the right than their counterparts in more homogeneous places, while poorer voters are more likely to vote for Partido Accion Nacional in less heterogeneous places. In more heterogeneous states, voters are more likely to encounter members of other socioeconomic groups who prompt them to vote for the party that better represents their group's interests.