Using a multilevel analysis method, this article tests different hypotheses for how income inequality affects voter support for radical right-wing parties (RRPs) in Western Europe. Specifically, the article shows how this ‘income inequality effect’ encourages poor people to vote for RRPs, while it concurrently discourages rich people from doing so. This finding supports the social identity hypothesis, which states that social identity (a micro-level factor) intermediates income inequality effect (a macro-level factor) on voter support for RRPs. The article's results suggest, further, that income inequality has different effects between the main supporters of RRPs with dissimilar occupations (e.g., manual workers and the petty bourgeoisie) because they belong to different income groups; and that country-level factors may have different effects on people regarding their support for RRPs.