Hume advances two negative claims about the source of the ordinary belief that one is the same person over time: this belief is not caused by perceiving a substance to which one’s perceptions belong; nor is it caused by perceiving real connections between perceptions. Hume’s positive account is that there is a felt connection among perceptions which, by associative processes involving causation and resemblance, induce the belief in personal identity. In the Appendix, Hume is satisfied with his negative claims but dissatisfied with his positive account. I offer an interpretation of his dissatisfaction. I argue that Hume cannot use causation or resemblance to connect present impressions with memories of past experiences to form the belief that I now am the person who also had that past experience. Furthermore, Hume’s explanations cannot retrospectively connect the believer in self with the self she believes in, without the painstaking work of distinguishing original perceptions and memories of them and tracing causal relations among distinct perceptions. Thus Hume fails to account for the ordinary belief that one is the same person over time.