Preface; Notes on contributors; 1. In defence of three-dimensionalism Kit Fine; 2. Modes of extension: comments on Kit Fine's 'In defence of three-dimensionalism' Peter Simons; 3. Two notions of being: entity and essence E. J. Lowe; 4. Essence and being Scott A. Shalkowski; 5. Micro-composition D. H. Mellor; 6. Working parts: reply to Mellor J. Robert G. Williams; 7. Truthmakers, realism and ontology Ross P. Cameron; 8. Monism and statespace structure Theodore Sider; 9. Coincidence and identity Penelope Mackie; 10. Nihilism without self-contradiction David Liggins; 11. Persistence and determination Katherine Hawley.