Fragile X syndrome (FXS) is the leading inherited cause of intellectual disability. The syndrome is caused by a single gene mutation on the X chromosome. Although individual differences are large, most individuals with FXS display weaknesses across all language and literacy domains compared with peers of the same chronological age with typical…

This article explores selected phonological measures, their relationships to one another, and how groups differentiated by such measures change over time during intervention. Relationships among global quantitative measures of severity (percent consonants correct), measures of variability/consistency, and measures of whole-word complexity and…