Many comprehensive rating scales have been developed to assess disabilities. These assessments, which require significant amounts of time, are usually performed by trained professionals. A simple case-finding instrument is needed to quickly identify older persons with potential disabilities, who then should undergo comprehensive assessments. In a cross-sectional study of 594 community-dwelling older subjects, we developed a questionnaire from an initial list of 23 yes/no questions, and compared it with an existing one to determine their relative ability to identify older persons with moderate to severe disabilities. Initially designed to identify older people with any disability, the existing seven-question tool also provided to be a good marker of significant disabilities, with a cut-off score of three or more positive answers. The sensitivity and specificity of this cut-off are 78.3% and 74.7%, respectively. These validity indices support the use of this questionnaire in identifying older persons with potential moderate to severe disabilities with a view to referring them for more comprehensive assessment.