Abstract: We exploit differential timing of abortion legalization across countries between 1960 and 2005 to estimate the effect of fertility on income, finding that reducing fertility by one child per women increases income per capita by about 20%. We estimate that most of the income gain is due to an increased number of workers per capita, because of a lower youth dependency ratio, and higher female labor force participation. We find little evidence that fertility reductions lead to increases in education, or the capital/labor ratio, but our theory suggests these effects may appear after several generations of lowered fertility.