BackgroundThis study is a longitudinal follow‐up to prior work examining the important pragmatic skill of communication repair (i.e., the ability to respond effectively to a request for clarification of an unclear message) across three neurodevelopmental disabilities in which language skills are impaired: fragile X syndrome with and without autism spectrum disorder (FXS‐ASD; FXS‐O), idiopathic ASD (ASD‐O), Down syndrome (DS) and controls with typical development (TD). Prior work examining communication repair skills at younger ages indicated impairments in boys with FXS‐ASD and ASD‐O, with females performing comparably with each other across groups.AimsTo characterize communication repair skills in young individuals with FXS‐ASD, FXS‐O, ASD‐O, DS and TD, across groups and over development. A secondary aim included documenting sex differences in FXS (with and without ASD) and DS.Methods & ProceduresSixty young individuals with FXS‐ASD (49 males, 11 females), 38 with FXS‐O (13 males, 25 females), 38 with ASD‐O (males only), 42 with DS (21 males, 21 females) and 41 with TD (21 males, 20 females) participated in the study, with a subsample reported on here who were retested at a second time point 2.7 years later on average. Participants completed a structured, picture‐based task designed to assess the ability to repair breakdowns in communication. Participants’ responses were compared across groups and sexes at the second time point, and interpreted with respect to previously published (Time 1) findings.Outcomes & ResultsKey findings included that, with age, male groups (including those with FXS‐ASD and ASD‐O, who showed difficulty at Time 1) performed more comparably, decreasing their use of inappropriate responses, in spite of relatively little change observed in general cognitive or structural language abilities in the clinical groups. However, girls with FXS and DS became more non‐responsive with age, and differences between boys and girls with FXS‐ASD emerged over time as well.Conclusions & ImplicationsFindings suggest that impairments in a critical pragmatic skill—the ability to repair communication breakdown—show significant change with age across three neurodevelopmental disabilities, with important sex‐specific patterns. These developments were often observed in spite of a relative plateau in cognitive and language growth, suggesting that repair skills may be more malleable and therefore an excellent target for intervention. Findings not only inform the nature of pragmatic impairment across groups but also can importantly inform clinical practice, suggesting that clinicians should monitor pragmatic skills such as repairs throughout development and also consider the role of sex in clinical efforts.