The exact causes of (and lessons from) the Great Compression – the decline in US income inequality in the mid-20th century – remain unclear. This column uses census data and changes in law to examine the effect of education across the complete distribution of income. Policies that increased attendance for young children in the late 19th and early 20th centuries appear to have had long-term implications for earnings and inequality, with returns to schooling highest among those at the lower end of the income distribution.