Scientists have long employed puppets in research with young children; this essay explores the validity of this practice. After considering what puppets are, their main types and history, I note the different ways puppets have been employed in research. One of these uses raises the issue of whether and when children apply their theory of mind to puppets. After exploring this issue, I consider if children believe puppets actually are animate and sentient, like humans, and whether children participating in experiments with puppets are pretending (in the sense of pretend play) that puppet stimuli are human. Children aged three years and older and infants are discussed separately, as different definitions of puppets have been used in the research across these age levels and different patterns of results have been obtained. I end with ideas regarding further research.