This article analyses the microeconomic sources of wage inequality in the United States from 1967–2012. Decomposing inequality into factors categorized by degree of personal responsibility, education explains over twice as much of inequality today as 45 years ago. However, neither hours worked nor education, industry, marital status, or geographical location can explain the rise in income inequality. In fact, ‘unfair’ inequality (income disparity derived from non-responsibility factors) has risen faster than ‘fair’ inequality (income disparity derived from responsibility factors), regardless of the set of variables chosen as fair sources of inequality. We further examine income inequalities within gender and racial groups, finding substantial heterogeneity. Overall, using micro data to understand the sources of inequality and how these changes over time can provide better information for policymakers motivated to combat rising inequality.