What do we know about wealth inequality and democracy? Our review shows that the simple conjectures that democracy produces wealth equality and that wealth inequality leads to democratic failure are not supported by the evidence. Why are democracy and high levels of wealth inequality sustainable together? Three key features of democratic politics can make this outcome possible. When societies are divided along cleavages other than wealth, this can inhibit the adoption of wealth-equalizing policies. Likewise, voter preferences for the redistribution of wealth depend on the beliefs they form about the fairness of these measures, and some voters without wealth may feel that redistribution is unfair. Finally, wealth-equalizing policies may be absent if the democratic process is captured by the rich; however, the evidence explaining when, where, and why capture accounts for variation in wealth inequality is less convincing than is often claimed. This phenomenon is a useful avenue for future research.