Having coined the word ‘eugenics’ and inspired leading biologists and statisticians of the early twentieth century, Francis Galton is often studied for his contributions to modern statistical biology. However, whilst documenting this part of his work, historians have frequently neglected crucial aspects of what motivated Galton to establish his eugenics research programme. Arguing that his work was shaped more by social than by biological science, this paper addresses these oversights by tracing the development of Galton's programme, from its roots in a debate about political economy to his appeals for it to be taken up by sociologists. In so doing, the paper not only returns Galton's ideas to their original context but also provides a reason to reflect on the place of the social sciences in history-of-science scholarship.