Peter Simons, Professor of Philosophy, Trinity College, Dublin, gives a talk as part of the series 'Metaphysics of Powers, Causation and Persons'. A process ontology (Heraclitus, Whitehead, Rescher) takes spatiotemporally extended events and processes as primary entities, enduring things as secondary. A factored ontology (Empedocles, Aristotle, Ingarden) investigates the non-entities in virtue of which there is categorial diversity in the world. Their combination purports to be a grounded universal ontological framework. As such it has not only to account for appearances but also to offer satisfactory solutions to known metaphysical difficulties such as the nature of causation, the status of spacetime, the regularity of the universe, the role of structure, and the emergence of mind. This talk will outline such an ontology and consider how far it does and can meet such desiderata.