BackgroundIn secure residential facilities, group climate perceptions of clients with mild intellectual disability or borderline intellectual functioning are systematically assessed for quality improvement. A valid and reliable measure may ensure that this process is consistent. The Group Climate Inventory—Revised (GCI‐R) is a new measure to assess group climate perceptions.MethodConfirmatory factor analysis was conducted in 148 adult clients (79% male) with mild intellectual disability or borderline intellectual functioning in a secure facility to examine internal structure validity and internal consistency reliability of the GCI‐R.ResultsThe results indicate support for the five‐factor structure of the GCI‐R (‘Support’, ‘Growth’, ‘Repression’, ‘Peer interactions’, and ‘Physical environment’). The internal consistency reliability of its scales ranged from acceptable to good (α: .72–.87; ω: .76–.86).ConclusionThe GCI‐R demonstrates evidence of psychometric adequacy when applied to adult clients with mild intellectual disability or borderline intellectual functioning in secure residential facilities.