It is widely recognised that stress can have a profound effect on individual lives. For organisations, stress has been shown to have considerable impact on several outcomes such as employee absenteeism, turnover, and injury rates. As work-related motor vehicle crashes have been shown to be the major source of workplace fatalities it is considered important to quantify the role of stress in fleet driving. Previous studies have shown that stress from life events has been associated with increased crash involvement. Accordingly, this study aimed to investigate how stress from daily hassles (outside of work) may impact upon driving lapses, errors, and violations for drivers of Queensland Government fleet vehicles. Participants (N = 247) completed a modified version of the Daily Stress Inventory, the Driver Behaviour Questionnaire (DBQ), and a brief questionnaire for demographic and exposure information. Hierarchical multiple regression revealed that after controlling for age, gender, and hours per week driving, daily hassles significantly predicted DBQ scores. This suggests that drivers’ subjective responses to specific antecedent events (e.g., hassles at home) places them in a vulnerable state that affects their driving behaviour. This is discussed in terms of Matthews’ (2001) Transactional Model of Driver Stress. The implications of the research are discussed, including the need for organisations to consider the far reaching effects of stress and the associated costs in terms of fleet safety and, accordingly, address such issues within organisational policies and procedures.