Is early reasoning about an agent's knowledge best characterized by a mentalistic stance, a teleological stance, or both? In this research, 5-month-old infants (N = 64, 50% female, 83% White) saw a novel eyeless agent consistently approach object-A as opposed to object-B. Although infants could always see both objects, a screen separated object-B from the agent. When object-B protruded above the screen, infants interpreted the agent's actions as revealing a preference for object-A over object-B. When object-B did not protrude above the screen, however, infants refrained from attributing such a preference: Consistent with mentalistic accounts, they reasoned that the agent's representation of the scene did not include object-B, and they used the agent's incomplete representation, non-egocentrically, to interpret its actions.