Williams syndrome (SW) is a neurodevelopmental disorder with a rare prevalence and is characterized by having a neuropsychological profile defined by better verbal than visuospatial abilities. The objective of the work was to improve the attentional, visuospatial and memory processes in a patient with SW through the application of a neuropsychological intervention program. The program was carried out for a year with an evaluation-intervention-evaluation design; the results of the second evaluation were compared with a clinical sample. For the analysis of the results, the reliable change index was used, to identify significant clinical changes before and after the intervention. It was found that the processes of sustained attention, inhibitory control, abstraction, working memory, visuospatial abilities and memory presented a significant clinical improvement. These results provide evidence of the importance of neuropsychological intervention in patients with SW to improve their quality of life.