This study tests whether overimitation is subject to an audience effect, and whether it is modulated by object novelty. Eighty-six 4-to-11-year old children watched a demonstrator open novel and familiar boxes, using sequences of necessary and unnecessary actions. The experimenter then observed the child, turned away, or left the room while the child opened the box. Children copied unnecessary actions more when the experimenter watched or when she left, but copied less when she turned away. This parallels infant studies which suggest that turning away is interpreted as a signal of disengagement. Children displayed increased overimitation and reduced efficiency discrimination when opening novel, compared to familiar boxes. These data provide important evidence that object novelty is a critical component of overimitation.