Causal accounts of the transtemporal identity of physical objects and of persons are not completely new. Passages in Hume can be read as suggesting causal accounts of the identity of physical objects and of the self, as can Kant's arguments that the successive states of an objective substance must be causally connected; and in this century, a variety of causal accounts of the identity conditions for persons and for physical objects have been proposed. Such accounts, especially for physical objects, have not been very fully developed, however, and here I want to provide a more detailed motivation for, and development of, a causal account of identity through time and to examine some of its implications. I think that my general line of argument applies both to persons and to physical objects, though to keep the discussion manageable I shall concentrate on the latter.