J. S. Mill and Henry Sidgwick's versions of classical utilitarianism have had an enormous effect on the development of modern English-speaking ethical philosophy. This study traces the impact of their thinking at Oxford and Cambridge during the second half of the nineteenth century and first half of the twentieth century, when analytical philosophizing began to emerge. It shows how much idealists such as T. H. Green and F. H. Bradley, ideal utilitarians such as G. E. Moore and Hastings Rashdall, and later intuitionists like W. D. Ross, H. A. Prichard, A. C. Ewing, and C. D. Broad owed to them, despite what the received view has assumed. It also explores how their impact was entangled with evolutionary theorizing in the aftermath of Darwin.