AbstractObjectiveTo validate the original and a shortened version of the Detail and Flexibility (DFlex) Questionnaire.MethodConfirmatory factor analyses, internal consistency, and discriminant validity estimates were conducted within individuals with a diagnosis of an eating disorder (ED) (n = 124), an anxiety disorder and/or depression (n = 219), and a community sample (n = 852) (Part 1). Convergent validity of the DFlex through comparisons with the Autism Spectrum Quotient, Wisconsin Card Sorting Task, and Group Embedded Figures Task was undertaken within a combined ED and community sample (N = 68). Test‐retest reliability of the DFlex was also examined across 2 years in a community sample (N = 85) (Part 2).ResultsThe original factor structure of the DFlex was not supported. Hence, a shortened version, the DFlex‐Revised, was developed. Good discriminant validity was obtained for the DFlex and DFlex‐Revised, however, support for convergent validity was mixed. Finally, the 2‐year test‐retest reliability for the two DFlex versions was found to be low, suggesting potential malleability in construct over this timeframe.ConclusionsFurther research is needed to validate the DFlex in clinical and non‐clinical populations using different neurocognitive tests. Test‐retest, using varied time intervals, should also be assessed.