ABSTRACT
One of the first tasks facing a clinician or clinical researcher is to describe the patient by assigning a diagnosis. Diagnoses do two very important things. First, they describe what disorder a person has and second, they impose a value judgment as to whether they are ill. Diagnostic systems are useful because they provide a common language for mental health professionals, researchers, and policy makers to discuss mental disorder. The DSM-IV (1994) and the World Health Organization’s International Classification of Disease (ICD, 1992) are the best-known diagnostic systems. Both are used worldwide. There is a great deal of agreement between the systems, and each provides equivalent diagnostic codes for the other. The diagnoses contained in these systems have been developed by committees of experts to ensure that each diagnostic category fairly reflects what clinicians and experts report having observed in their patients.
