Child and adolescent psychiatry: past scientific achievements and challenges for the future.

The worldwide history of scientific achievements in child and adolescent psychopathology is reviewed from the mid-twentieth century onwards. Attention is drawn, e.g., to diagnostic distinctions, measures of psychopathology, the several roles of epidemiological longitudinal studies, temperament and personality, developmental psychopathology, the use of 'natural experiments' to test causal inferences, environmental risks, the importance of gene-environment interplay, the relative coming together of initially diverse psychological therapies, the use of randomized-controlled trials to assess treatment efficacy, and the value and limitations of pharmacotherapy. The article ends with a look ahead to the most important opportunities and challenges for child and adolescent psychiatry, plus the hazards that need to be avoided.