Investigates the potential role of `basic communicative acts' (pointing gestures, yes/no signs, object-offer, object-request, attention-getting signals, and many others) for human-robot interaction. Argues that BCAs constitute a strategy for implementing natural HRI because they are (1) non-linguistic, hence simpler than language-based signals, (2) while simultaneously permitting sophisticated human-robot cooperation. Draws on evolutionary theory and research on embodied cognition (`affordances'). Discusses some of the challenges involved in implementing embodied systems that comprehend BCAs. The chief problem will be to design systems that use context.