Preface; 1. Introducing substance concepts; 2. Substances: the ontology; 3. Classifying, identifying, and the function of substance concepts; 4. The nature of abilities: how is extension determined?; 5. More mama, more milk and more mouse: the structure and development of substance concepts; 6. Substance concepts through language: knowing the meanings of words; 7. How we make our ideas clear: epistemology for empirical concepts; 8. Content and vehicle in perception; 9. Sames versus sameness in conceptual contents and vehicles; 10. Grasping sameness; 11. In search of Strawsonian modes of presentation; 12. Rejecting identity judgments and Fregean modes; 13. Knowing what I'm thinking of; 14. How extensions of new substance concepts are fixed: how substance concepts acquire intentionality; 15. Cognitive luck: substance concepts in an evolutionary frame; Appendices; References; Index.