The purpose of this study was to characterize wheelchair tiedown and occupant restraint system (WTORS) usage in paratransit vehicles based on observations of wheelchair and scooter (wheeled mobility devices, collectively, "WhMD") passenger trips. A retrospective review of on-board video monitoring recordings of WhMD trips was conducted. Four hundred seventy-five video recordings were collected for review and analysis. The use of all four tiedowns to secure the WhMD was observed more frequently for power WhMDs (82%) and manual WhMDs (80%) compared to scooters (39%), and this difference was significant (p< 0.01). Nonuse or misuse of the occupant restraint system occurred during 88% of WhMD trips, and was most frequently due to vehicle operator neglect in applying the shoulder belt. Despite the absence of incidents or injuries in this study, misuse and nonuse of WTORS potentially place WhMD seated passengers at higher risk of injury during transit. These findings support the need for improved vehicle operator training and passenger education on the proper use of WTORS and development of WTORS with improved usability and/or alternative technologies that can be automated or used independently.