Structure has played a significant role in recent philosophy of science, often at the expense of objects, but for Kathrin Koslicki structures and objects are inseparable: every composite material object has a structure, and the structure is literally a part of the object. Whilst she draws her inspiration – and her critical targets – from the metaphysical works of Plato and Aristotle, David Lewis and Kit Fine, Koslicki’s book contains much that will interest philosophers of science, perhaps especially philosophers of physics and of biology.