The validity of a measure of adjustment in siblings of children with developmental and physical disabilities: a brief report.

: Few questionnaires are tailored for siblings of children with disabilities. The Negative Adjustment Scale (NAS) was developed to measure siblings' adjustment, but has not yet been validated.: To investigate the factor structure and convergent validity of the NAS. We examined the validity of the NAS in terms of factor structure and convergent validity against a general mental health measure. The sample comprised 107 siblings ( age = 11.5 years,  = 2.1, 53.8% boys) of children with disabilities.: We confirmed a one-factor structure for the NAS. Convergent validity was demonstrated through significant correlations (=.29-.44) with sibling externalizing and internalizing mental health difficulties.: The NAS holds promise as a measure tailored for the assessment of sibling's adjustment.