In this paper I examine the concept of cross-temporal personal identity (diachronicity). This particular form of identity has vexed theorists for centuries -- e.g.,how can a person maintain a belief in the sameness of self over time in the face of continual psychological and physical change? I first discuss various forms of the sameness relation and the criteria that justify their application. I then examine philosophical and psychological treatments of personal diachronicity(for example,Locke's psychological connectedness theory; the role of episodic memory) (...) and find each lacking on logical grounds, empirical grounds, or both. I conclude that to achieve a successful resolution of the issue of the self as a temporal continuant we need to draw a sharp distinction between the feeling of the sameness of one's self and the evidence marshaled in support of that feeling. (shrink)