PURPOSE:To examine the internal consistency, construct validity and responsiveness of functional assessments tools when used with hospitalized older adults. MATERIALS AND METHODS:The functional ability of 66 patients was assessed using a semi-structured interview scale (n = 16 tools). The assessment of motor and process skills was administered during hospital admission and again at three months post-discharge. RESULTS:Tools showed poor-to-excellent internal consistency (α = 0.27-0.92). Of the tools that were internally consistent, only two demonstrated change: the Groningen activity restriction scale (GARS) (smallest detectable change [SDC] 11.68, effect size -1.59) and the modified reintegration to normal living scale (SDC 7.04, effect size -1.20). Validity was supported by strong correlations between the functional independence measure™ (FIM™) and the GARS, FIM™ and Sunnaas activity daily living (ADL) index. CONCLUSIONS:Findings suggest that the GARS and the modified reintegration to normal living index (mRNLI) are internally consistent, valid and responsive to change over time when applied to a sample of hospitalized older adults. Further investigation of these tools in terms of inter and intra rater reliability in clinical practice is warranted. Implications for Rehabilitation Therapists and researchers need to choose standardized functional assessments carefully when working with hospitalized older adults, as not all assessments are reliable and valid in this population. The GARS and mRNLI are valid and responsive functional assessments for hospitalized older adults. Activity and participation have been viewed traditionally as only one component of function. Therapists and researchers can use standardized assessments of function that are activity or participation-based.