Elite schools in the UK are bound to the history of British colonialism. This paper examines the material ties between these schools and the transatlantic slave trade. We combine multiple sources to examine which schools and their alumni accrued substantial economic capital derived from the enslavement of Black people. We find two principal connections: first, in donations and foundations of schools from those who made their fortune in the slave trade; and second, through income of boys attending these schools. Drawing on the Legacies of British Slavery dataset, we show that schools with alumni benefitting from the slave trade include the most prestigious British private schools. Moreover, this paper traces the histories of several secondary schools founded by, or in receipt of, substantial donations from slave-owning families. We argue that extractive, violent forms of colonial capital accumulation have been central to, the formation and maintenance of these elite educational institutions.