Economic inequality is a defining issue of the 21st century. Past research has documented myriad pernicious psychological effects of high inequality, prompting interest into how people perceive, evaluate, and react to economic inequality. Here we propose, refine, and validate the Support for Economic Inequality Scale (SEIS) – a novel measure of attitudes towards economic inequality. In Study 1, we distill eighteen items down to five, providing evidence for unidimensionality and reliability. In Study 2, we replicate the scale’s unidimensionality and reliability and demonstrate its validity. In Study 3, we evaluate a United States version of the SEIS. Finally, in Studies 4 and 5, we show predictive validity by relating the SEIS, compared with conceptually similar measures, to two inequality-mitigating behaviors. The SEIS is a valid and reliable instrument for assessing perceptions of and reactions to economic inequality, and provides a useful tool for researchers investigating the psychological underpinnings of economic inequality.