1. Why use natural enemies? -- 2. Introduction to biological control -- 3. Classical biological control -- 4. Augmentation : inundative and inoculative biological control -- 5. Conservation and enhancement of natural enemies -- 6. Ecological basis for use of predators, parasitoids and pathogens -- 7. Predators -- 8. Insect parasitoids : attack by aliens -- 9. Parasitic nematodes -- 10. Bacterial pathogens of invertebrates -- 11. Viral pathogens -- 12. Fungi and microsporidia -- 13. Biology and ecology of agents used for biological control of weeds -- 14. Phytophagous invertebrates and vertebrates -- 15. Plant pathogens for controlling weeds -- 16. Biology and ecology of antagonists -- 17. Microbial antagonists combating plant pathogens and plant parasitic nematodes -- 18. Safe biological control -- 19. Present uses of biological control.