DescriptionFederal legislation requiring the inclusion of students with disabilities (SWDs) in standardized testing and annual accountability reports has increased the need for developmentally appropriate and psychometrically sound alternate assessments that are reflective of the state’s curricular standards. Few validated measures exist that adequately address the unique needs of this population and integrate evaluation of academic achievement and functional behavior, the latter having been deemed paramount for SWDs. The P.G. Chambers Outcomes Measurement Tool (PGS-OMT) assesses various areas of functioning of students with severe, multiple disabilities to glean a more representative depiction of their capabilities. The main goal of this study was to gather evidence to establish the reliability and validity of conclusions drawn from the scores of this rating scale. The PGS-OMT measures student outcomes and progress and includes assessment of skills in the following areas: Communication, Social, Personal Care, Physical Navigation, Academics, and Functional. The PGS-OMT was used to assess 117 students enrolled in an out-of-district placement in New Jersey. The PGS-OMT was found to be reliable with excellent internal consistency. Internal structure validity evidence was obtained via factor analyses and correlations between PGS-OMT domains. Results indicated a three-factor structure, further supported by the pattern of intercorrelations of PGS-OMT domains. The PGS-OMT shared substantial variance with an established measure of adaptive behavior. Although no significant differences were found between mean scores of advantaged and disadvantaged ethnic groups for two of the three factor domains, further investigation is required to assess instrument bias due to ethnic heterogeneity in the disadvantaged group. Teacher perceptions of the PGS-OMT were favorable and Evaluation Survey results supported the tool’s utility.