Contemporary metaphysics is dominated by the view that every object belongs to a kind permanently in the sense that it cannot cease to belong to that kind without thereby ceasing to exist. For example, some philosophers think that a person is destroyed if they cease to be a person, a statue is destroyed if it ceases to be a statue, and so on. I believe that this standard view is false. Being a person, or a statue, or etc., is like being a child: just as I did not cease to exist when I ceased to be a child, so people and statues need not cease to exist when they cease to be people and statues. Borrowing a term from Daniel Korman (who uses it in a similar but perhaps not identical way), I call this view phasalism because it entails that the kind-properties which ordinary objects instantiate are phase sortal properties, i.e., kind-properties that an object can instantiate for a temporary phase of its career. This dissertation is a partial defense of phasalism. I develop a phasalist metaphysics in detail, highlighting its virtues and rebutting objections along the way. After some stage-setting (Chapter 1), I defend a phasalist criterion of identity over time for ordinary objects (Chapter 2), as well as a phasalist account of the role that sortal properties play in the identity over time of ordinary objects (Chapter 3). Then I defend a phasalist-friendly approach to the identity over time of lumps, hunks, pieces, etc. of matter (Chapter 4). The material in these chapters amounts to a phasalist solution to certain material coincidence puzzles, such as the puzzle of the statue and the piece of clay. I go on to show that familiar puzzles about undetached parts (Chapter 5) and fission (Chapter 6) can be solved within the confines of my phasalist metaphysics as well.