Preface.- Introduction.- What are N-of-1 trials?- N-of-1 trials in the behavioural sciences.- N-of-1 trials in medical contexts.- Aggregated N-of-1 trials.- Methodological considerations for N-of-1 trials.- Randomization, allocation concealment and blinding.- Data collection and quality control.- Individual reporting of N-of-1 trials to patients and clinicians.- Assessing and reporting adverse events.- Research ethics and N-of-1 trials.- Statistical analysis of N-of-1 trials.- The economics of N-of-1 trials.- Reporting N-of-1 trials to professional audiences.- Single patient open trials.- Systematic review and meta-analysis using N-of-1 trials.- Where are N-of-1 trials headed?- Index.