According to the theory of appearing, veridical perception consists in an irreducible relation of appearing between a perceiving subject and a physical object. The paper sketches the development of the theory and its relation to competing views (sense data theory, adverbialism, representationalism). The most worked-out version of the theory, due to William Alston, is found lacking on several counts. First, Alston’s account of the phenomenal character of perception succeeds only if we disregard the possibility of illusion. Second, the account implies, implausibly, that to be deceived by hallucination is to commit an introspective error concerning the phenomenal character of one’s own experience. Another unintuitive implication of the theory is that veridical perception involves not one but two objects appearing to the subject: the physical object perceived and a further, special object required to account for the possibility of hallucinatory experience. Finally, relative to its competitors, the theory of appearing is not in a privileged position to explain how perception can be a source of justification for empirical judgements.