Recent research has shown that infants as young as 13 months can attribute false beliefs to agents, suggesting that the psychological-reasoning subsystem necessary for attributing reality-incongruent informational states (Subsystem-2, SS2) is operational in infancy. The present research asked whether 18-month-olds’ false-belief reasoning extends to false beliefs about object identity. Infants watched events involving an agent and 2 toy penguins; 1 penguin could be disassembled (2-piece penguin) and 1 could not (1-piece penguin). Infants realized that outdated contextual information could lead the agent to falsely believe she was facing the 1-piece rather than the 2-piece penguin, suggesting that 18-month-olds can attribute false beliefs about the identity of objects and providing new evidence for SS2 reasoning in the 2nd year of life.