In co-speech gesture research, embodied cognition implies that concepts are associated with haptic and motor information that provides a framework for a gestural plan. When speakers access concepts, embodied action images are automatically activated. This study considers situations in which speakers need to create online concepts of events to investigate the aspect of the event that forms the basis of a new concept. Speakers watched short event video clips with familiar or unfamiliar attributes. They described those clips to partners who had to perform a matching task. Experimental results show that speakers gestured less and produced shorter gestures when relaying longer event descriptions. Speakers were more likely to produce gesture when some aspect of the event was unfamiliar, and they were most sensitive to the familiarity of the event’s main action. Further, when speakers did gesture, they were most likely to gesture to represent the action of the event over the physical attributes of it (the instrument used to enact or the object acted upon). These findings suggest that in creating an embodied concept for something unfamiliar, the motion of the event acts as a basis for their online embodied representation of the concept.