Young children often treat robots as social agents after they have witnessed interactions that can be interpreted as social. We studied in three experiments whether four-year-olds from three cultures (China, Japan, UK) and adults from two cultures (Japan, UK) will attribute ownership of objects to a robot that engages in social gaze with a human. Participants watched videos of robot-human interactions, in which objects were possessed or new objects were created. Children and adults applied the same ownership rules to humans and robots irrespective of whether the robot engaged in social gaze or not. However, there was cultural variation in the types of ownership rules used. In Experiment 3, we removed further social cues, finding that just showing a pair of self-propelled robot-arms elicited ownership attributions. The role of social gaze in social attributions to robots and cross-cultural differences in ownership understanding are discussed.