Fragile X syndrome (FXS) is the leading inherited cause of intellectual disability. It is primarily caused by the expansion of a CGG trinucleodide repeat located in the 5′ untranslated region of the X‐linked FMR1 gene. Individuals with FXS present with variable intellectual quotients (IQs) ranging from the average to the severe intellectual disability level. A range of neurocognitive strengths and challenges are observed in individuals with FXS. This article provides an overview of our current understanding related to cognition and FXS. Cognitive functioning levels, profiles, and IQ trajectories are discussed. Limitations of existing neuropsychological measures are described. For further resources related to this article, please visit the WIREs website. Conflict of interest: The authors have declared no conflicts of interest for this article.