This article reviews the development of the DSM diagnosis of Generaliz
ed Anxiety Disorder (GAD). Generalized Anxiety Disorder is a common, c
hronic, and very distressing disorder. However, it has rarely been emp
irically investigated. This lack of research was mainly caused by the
difficult diagnosis of GAD. The DSM classification system has been cha
nged several times in order to improve the reliability of the diagnosi
s. As the changes were made, the worries of GAD patients became the di
stinctive symptom of the disorder. Unfortunately, the phenomenon of wo
rrying has not been well investigated either. Empirical studies of wor
ries are reviewed and their relevance for the diagnosis of GAD is disc
ussed.