ABSTRACT Williams syndrome (WS) is a contiguous gene syndrome caused by hemizygous deletion of approximately 30 genes on chromosome 7q11.23, resulting in a phenotype including cardiovascular abnormalities, elfin faces, and mental retardation. Individuals with WS are known to display rich, expressive verbal abilities with friendly personality and well preserved facial recognition, namely exquisite communication ability at the first face. Conversely, visuo-spatial abilities are extremely poor. Some researchers have thus assumed that WS is a rare congenital disease causing specific clinical manifestation similar to neuropsychological dissociation in adult braindamaged patients, arousing the interest of cognitive neuroscientists. This clinical dissociation initially appeared to support the idea that a specifically preserved function in individuals with WS is linguistic. However, recent studies have verified that the entire cognitive function in WS is constructed differently. In addition, some of the approximately 30 genes in the deleted region of the chromosome are expressed in the brain, suggesting that those absent genes are related to the development of the unique pattern of cognitive function pattern in WS. The present article provides an overview of cognitive neuropsychological research into WS, from early studies to more recent investigations, and then traces the historical transition of research in this discipline.