Despite the fact that controversy over racial profiling has brought police activities and discretion under public scrutiny, relatively little research has focused on how police officers use their discretion in traffic enforcement encounters. The current study relied on field observations and interviews with police officers to explore how the officers used discretion, particularly leniency, in traffic enforcement encounters. Students being trained to conduct systematic social observations of police officers observed 151 traffic stops during 288 hours of ride-along observations. Students also interviewed 13 officers and supervisors from the patrol division regarding their observations of how police spent their time and performed their duties. The results focus on how officers made decisions, particularly in terms of whether to stop and to sanction, and the factors that influenced those decisions. The findings indicated that leniency in sanctioning was common provided motorists lived up to officers’ expectations in terms of their behavior (contrite) and their acknowledgment of responsibility for the infraction. Results are discussed at two levels: the psychology of the individual officer and the organizational dynamics of the traffic stop. Given that little was learned about the cognitive mechanisms used by officers during traffic stops, future research should focus on exploring the questions officers ask themselves when confronting citizens in the course of their police duties. Tables, notes, references