1. Epidemiology is ...; 2. How long is a piece of string? Measuring disease frequency; 3. Who, what, where and when? Descriptive epidemiology; 4. Healthy research: study designs for public health; 5. Why? Linking exposure and disease; 6. Heads or tails: the role of chance; 7. All that glitters is not gold: the problem of error; 8. Muddied waters: the challenge of confounding; 9. Reading between the lines: reading and writing epidemiological papers; 10. Who sank the boat? Association and causation; 11. Assembling the building blocks: reviews and their uses; 12. Surveillance: collecting health-related data for epidemiological intelligence and public health action with Martyn Kirk; 13. Outbreaks, epidemics and clusters with Martyn Kirk and Adrian Sleigh; 14. Prevention: better than cure?; 15. Early detection: what benefits at what cost?; 16. Epidemiology and the public's health.