I have just belaboured causal theories of acting and having something happen to oneself. Now I want to make a fresh and more positive approach to these traditional categories. I shall begin with a few clear examples that we might select from the incidents of a person's life. If a man walks or steals, he does something. If he is carried or robbed, something happens to him. If what befalls him is momentous - if he submits to surgery or a liedetector test, for instance - then we say that he undergoes something. For expository convenience, however, I shall equate undergoing and having something happen to one. The philosophical question with which I shall approach the concepts of doing and undergoing is this: although we have no trouble multiplying instances of both types of occurrence, do we understand what qualifies them for these categories? In other words, what makes our examples cases of doing or undergoing? My point of departure will be the verbs and verb phrases we use to report events in which a human being figures prominently. Thus I shall not be concerned with the 'actions' of inanimate objects and forces, such as the action of hydrochloric acid upon copper, or the behaviour of animals. I shall assurne that the sense in which inanimate things act is different from the sense in which people act. One reason Iassume this is that it sounds unintelligible to assert that the hydrochloric acid deliberately stained the copper, or that it did so by accident; whereas these adverbs combine intelligibly with the statement that a jeweller stained the copper. As for animals, I take it that their behaviour is partly analogous to human deeds.