1. Introduction
2. SDSS DR7: Definition of the Sample
3. Mock Millennium I Catalogue: Definition of the Sample
4. Void-Finder Algorithm
5. Voids in the SDSS DR7 Redshift Survey and in the Mock Catalogue
6. Abundance of Large Voids: The SDSS DR7 Observation Versus the Mock Catalogue
7. Observed SDSS Voids Are Less Luminous Than Those in the Mock Catalogue
8. Conclusion