Throughout the 19th century and until the mid-20th century, in terms of long-term investment in human capital and, above all, in education, Spain lagged far behind the international standards and, more specifically, the levels attained by its neighbours in Europe. In 1900, only 55% of the population could read; in 1950, this figure was 93%. This paper provides evidence that these conditions contributed to a pattern of slower economic growth in which the physical strength required for agricultural work, measured here through height, had a larger impact than education on economic growth. It was not until the 1970s, with the arrival of democracy, that the Spanish education system was modernized and the influence of education on economic growth increased.