19Previous research suggested that 16--week old dog pups, but not wolf pups, 20show attachment behaviour to a human caregiver. Attachment to a caregiver in dog 21 pups has been demonstrated by differential responding to a caregiver compared to 22 a stranger in the Ainsworth Strange Situation Test. We show here that 3--7 week old 23 wolf pups also show attachment--like behaviour to a human caregiver as measured 24 by preferential proximity seeking, preferential contact, and preferential greeting to 25 a human caregiver over a human stranger in a modified and counterbalanced 26 version of the Ainsworth Strange Situation Test. In addition, our results show that 27 preferential responding to a caregiver over a stranger is only apparent following 28 brief isolation. In initial episodes, wolf pups show no differentiation between the 29 caregiver and the stranger; however, following a 2--min separation, the pups show 30 proximity seeking, more contact, and more greeting to the caregiver than the 31 stranger. These results suggest intensive human socialization of a wolf can lead to 32 attachment--like responding to a human caregiver during the first two months of a 33 wolf pup's life. 34