Intellectual disability (ID) is a common and highly heterogeneous neurodevelopmental disorder. The prevalence of ID is around 1%–3% in the general population. ID is associated with a wide range of additional neurological disabilities and the results of various studies have disclosed the co-morbidity of ID and ataxia. The aim of this review is elucidation of the common molecular and cellular pathways in the etiology of ID and ataxia. Categorization of these genes with various cellular functions indicates several genetic collisions in the co-occurrence of ID and ataxia.