Income redistribution differs widely across countries. Several theories have been developed to account for such differences. However, we know little about their relative importance. This working paper fills this gap by contrasting the main theories of preferences for redistribution in a unified empirical framework. Using nationally representative samples of Germany, Italy, Japan, Slovenia, the UK and the US, we find that the belief in equal opportunities to get ahead in life is the strongest predictor of demand for redistribution. The perception of immigrants as a threat significantly reduces preferences for redistribution, whereas other factors such as self-interest, social capital, and experimentally measured pro-sociality play lesser roles. We uncover significant cross-country heterogeneity; for instance, beliefs in equal opportunities strongly influence redistribution preferences in the US, UK, and Germany but are less impactful elsewhere. Contrary to previous research, beliefs in equal opportunities show no significant differences by political orientation, indicating a widely accepted, ideologically neutral view of fairness.