This experimenter was either the same person who had engaged in the warm-up with the toddler or a completely unfamiliar adult. Toddlers were more likely to smile at, and engage in synchronic imitation with, the familiar experimenter than the unfamiliar experimenter. This suggests that by 2 years of age, children’s affiliation with, and imitation of, the model is facilitated by familiarity. The fact that these differences are seen after a 10-min warm-up indicates that the effects of familiarity can be achieved after a relatively brief interaction. However, it is possible that this facilitative effect may be specific to live interactive contexts and might not extend to contexts in which children simply witness third-party interactions and do not interact at all with the model.