The effective integration of traditional psychometric assessment and behavioural assessment, in research as well as in practice, is discussed in this detailed and critical review. The important questions of whether integration can improve the quality of the information collected, strengthen the validity of interpretations and improve reliability are also explored. Systematically examining both literatures, Silva shows how an integration of psychometric principles with behavioural assessment standards can have positive results. Beginning with a review of the origins of behavioural assessment through to current practices, Silva explores the arguments for and against integration. He goes on to discuss the possibility of a normative interpretation of behavioural assessment data and how recent advancements in the psychometric approach to reliability and validity can enhance behavioural assessment.