One example is that drivers classified as obese were significantly more likely to be rated as fatigued, to be involved in a safety-critical event, and to be involved in safety-critical events related to fatigue.[1] Another naturalistic driving study of local and short-haul truck drivers found that 8 of the 42 drivers in the study accounted for 60% of the 77 safety-critical events documented.[23] In progress at VTTI is a case-control study that seeks to differentiate commercial drivers who are involved in a crash from those who are not according to individual and organizational characteristics.[24] This line of research has implications to improve trucking safety by identifying attributes of higher-risk individuals and implementing controls to monitor and improve their safety performance.