Assisted colonization, or the translocation of species threatened with extinction to habitats outside their indigenous range (usually as a response to predicted climate shifts), is a divisive issue for conservationists. Yet, history shows that wildlife scientists were discussing the trade-offs and challenges of translocating species for conservation purposes, including introducing them to new habitats, long before anthropogenic climate change was recognized as posing a conservation problem. Here we examine a case of the scientific and policy deliberations of a high profile group of scientists and policy advisers from the 1960s (the U.S. Bureau of Sport Fisheries and Wildlife's Committee on Rare and Endangered Wildlife Species) to provide a useful historical context for assessing current debates on assisted colonization. The Committee's attempt to produce a consistent policy for the ‘transplantation’ of threatened species illustrates how translocation debates have long hinged on an unresolved set of scientific and conceptual concerns, including the relative value of individual species and historically intact ecosystems and the philosophical status of human-assisted movement of wildlife. Bringing the Committee's deliberations to light places contemporary debates over assisted colonization in the USA in their historical context and illustrates how what often appear to be highly technical and scientific disagreements over conservation translocations are ultimately driven by deeper conceptual issues about the means and ends of conservation.