Developmental researchers are well aware that children behave differently around different people. Nevertheless, researchers rarely consider (and report on) who is running their studies. Indeed, in a survey of articles published in the last 3 years in 4 top developmental journals, we find that the vast majority of studies fail to report any information about experimenter identity, despite the fact that child–adult interactions may be strongly influenced by the social inferences that individuals draw from one another. We argue that developmental researchers need to acknowledge how experimenter identity could be acting as an invisible, lurking variable, influencing the outcome and generalizability of studies. We provide simple suggestions for how researchers and journals can begin to address this issue, thereby improving the quality and depth of the work in our field.