This book is concerned with the relations between graphs, error-correcting codes and designs.

1. A brief introduction to design theory; 2. Strongly regular graphs; 3. Quasi-symmetric designs; 4. Partial geometries; 5. Strongly regular graphs with no triangles; 6. Polarities of designs; 7. Extensions of graphs; 8. 1-factorisations of K6; 9. Codes; 10. Cyclic codes; 11. Threshold decoding; 12. Finite geometries and codes; 13. Self-orthogonal codes, designs and projective planes; 14. Quadratic residue codes; 15. Symmetry codes over GF(3); 16. Nearly perfect binary codes and uniformly packed codes; 17. Association schemes.