The communicative interactions of very young children almost always involve language (based on conventions), gesture (based on bodily deixis or iconicity) and directed gaze. In this study, ninety-six children (3;0 years) were asked to determine the location of a hidden toy by understanding a communicative act that contained none of these familiar means. A light-and-sound mechanism placed behind the hiding place and illuminated by a centrally placed switch was used to indicate the location of the toy. After a communicative training session, an experimenter pressed the switch either deliberately or accidentally, and with or without ostension (in the form of eye contact and child-directed speech). In no condition did she orient towards the hiding place. When the switch was pressed intentionally, children used the light-and-sound cue to find the toy – and tended to do so even in the absence of ostensive eye contact. When the experimenter pressed the switch accidentally, children searched randomly – demonstrating that they were tracking her communicative intent, and not merely choosing on the basis of salience. The absence of an effect of ostension contradicts research that ostension helps children to interpret the communicative intentions underlying unfamiliar signs. This is explained by concluding that while it may play a role in establishing a communicative interaction, it is not necessary for sustaining one; and that even with a highly novel communicative act – involving none of the means of communication on which children typically rely – three-year-olds can comprehend the communicative intentions behind an intentionally produced act.