It has recently been shown that children selectively imitate the actions of individual in-group members. The present studies examined whether group-based selective imitation occurs even in implicit, speeded imitation. Participants were 20 adults, and 44 children distributed across two age groups (5th graders, 2nd graders). Participants were told to press a mouse-key as fast as they could, in response to the ipsilateral hand movements modeled on a computer-screen. Manipulated across trials were: a) whether participants responded alone (i.e., as individuals) or jointly with a confederate (i.e., as a group), b) whether one (i.e., an individual) or two hands (i.e., a group) modeled the action, and c) whether the modeled hands belonged to participants’ ethnic in-group (Israeli Jews) or out-group (Arabs). Overall, results showed that although models’ group membership did not affect adults’ response times, it did affect children's. Namely, children responded faster to in-group than out-group hands when two hands modeled the action. These findings demonstrate the existence of automatic inter-group biases in young children's imitation.