There is no obvious line or boundary that separates wild animals from those that are not wild. Instead, there are expansive grey areas, of which the most conspicuous encompass the domesticated animals that have reverted to a life outside human control, and the undomesticated animals that thrive within human environments. To examine this dynamic, this article looks at “acclimatisation societies,” which first appeared in the nineteenth century. These societies, which flourished particularly in Australia and New Zealand, sought to breed animals to make them more suitable for domestic purposes.