Light's Timed-Functional-Movements (TFMs) battery is a timed functional mobility assessment for older persons. The purpose of the current study was to investigate the concurrent validity of on-site to videotape timing of the TFMs, followed by interrater, intrarater, and test-retest reliability of the TFMs battery with a frail, elderly population. Twenty frail, elderly subjects participated in two test sessions. Test movements were timed and videotaped on-site by a primary examiner. After establishing the high concurrent validity of videotape timing, the interrater, intrarater, and test-retest reliability of the TFMs were examined by videotape timed measures. This methodology was chosen to allow the test-retest reliability of the client's performance to be separated from the therapist's intrarater reliability. Reliability measures were calculated using intraclass correlation coefficients (ICCs; 2,1). The concurrent validity of videotape timing to on-site timing ranged from ICC = .90-1.0. Interrater ICCs for both self-selected and maximum speeds were .97 or greater. Exceptions were self-selected-speed lie to sit (.87) and maximum-speed stand to sit (.88). Ail intrarater ICCs were .98 or greater. Test-retest ICCs varied by movement. In conclusion, the TFMs Battery is easily administered, has high interrater and intrarater reliability, moderate to high test-retest reliability, and high concurrent validity of the on-site to videotape analysis. When close guarding of the client is required during the on-site assessment, the therapist may videotape the TFMs and later complete the analysis.