The author argues that events, not substances, are the fundamental units of reality. What kinds of things are events? Battles, explosions, accidents, crashes, rock concerts would be typical examples of events and these would be reinforced in the way we speak about the world. Philosophers following Aristotle have claimed that events are dependent on substances such as physical objects and persons. But with the advances of modern physics, some philosophers and physicists have argued that events are the basic entities of reality and what we perceive as physical bodies are just very long events spread out in space time. In other words, everything turns out to be events. This view, no doubt, radically revises our ordinary common sense view of reality, but as our event theorists argue, common sense is out of touch with advancing science. Leemon McHenry argues that Whitehead's metaphysics provides a more adequate basis for achieving a unification of physical theory than a traditional substance metaphysics. He investigates the influence of Maxwell's electromagnetic field, Einstein's theory of relativity and quantum mechanics on the development of the ontology of events and compares Whitehead's theory to his contemporaries, C. D. Broad and Bertrand Russell, as well as W. V. Quine. In this way, McHenry defends the naturalized and speculative approach to metaphysics as opposed to analytical and linguistic methods that arose in the 20th century. Features: clear exposition of the affinities in the revisionary theories of Alfred North Whitehead, Bertrand Russell and W. V. Quine regarding the proper relationship between philosophy and science; explains the arguments against the substance view of Aristotle and his followers with reference to the descriptive approach of ordinary language philosophy; and, updates event ontology of the 1920s with 21st century developments in physics and cosmology, especially with respect to progress on a final, unifying theory.