This study tested the hypothesis that seat belt usage is related to driver risk taking in car-following behavior. Individual vehicles on a Detroit area freeway were monitored to identify seat belt users and nonusers. Headways between successive vehicles in the traffic stream were also measured to provide a behavioral indicator of driver risk taking. Results showed that nonusers of seat belts tended to follow other vehicles closer than did users. Users were also less likely than nonusers to follow other vehicles at very short headways (one second or less). The implications of these findings for occupant safety in rear end collisions are discussed.