i-iv -- Acknowledgements -- Table of contents -- List of Tables and Figures -- Abbreviations and Conventions -- 1. Introduction -- 2. Lexical-Semantic and Syntactic Aspects of Factivity -- 3. Presupposition and Factivity -- 4. The Structure of Factive and Nonfactive Sentences -- 5. Factivity in Language Acquisition -- 6. Towards a Developmental Model -- 7. Experimental Studies -- 8. Conclusion -- Appendix -- References