Written for the non-clinical researcher as well as for those with clin ical experience, the authors start by considering the question "what i s psychopathology?" They tehn employ a historical perspective to expla in why and how mental disorders are currently classified, and how the use of an operational approach to diagnosis was adopted. The use of op erational crtieria to define psychiatric disorder has facilitated the development of standardised interviewing techniques, questionnaires an d rating scales. These tools are all covered in some detail, not only with regard to adults with mental...