During the last decades the number of employees working in flexible and/or unsocial hours (e.g., on evenings and weekends) has substantially increased. However, working on weekends can reduce both recovery time and interfere with the social rhythm in our society, thus reducing the amount of socially valuable hours available. According to the social rhythm, the utility of time for social and leisure activities is usually rated higher in the evenings and on weekends, with the highest values on Sundays. Thus, working on Sundays should lead to severe impairments to psychosocial well-being, to a reduction in the quality of and time for recovery from work-related strain, as well as to a reduction of social commitments. However, only very few studies have addressed possible safety, health, and social effects of work on Sundays yet. Furthermore, the effects of working on Sundays and working in shifts, which often includes work on Sundays, have not been separated yet. The objectives of our study were therefore to investigate in two large and representative samples of the European workforce, whether working on Sundays increases the risk of impairments to (1) occupational safety, e.g. as expressed in the incidence of accidents, (2) general health, and (3) work-life balance, while controlling for different important confounders. Two representative samples of employed workers in the 15 original member states of the European Union served as the data base for a cross-sectional analysis. The samples were collected via face-to-face interviews in the year 2000 (EU 2000) and 2005 (EU 2005) and contained data of n=17,910 and n=12,288 individuals in 2000 and 2005, respectively. The surveys included questions on working conditions, several work schedule characteristics, and the individual personal situation (e.g., demographic information, time lost due to an occupational accident in the last 12 months, subjective health impairments, subjective compatibility between working hours and private/ leisure commitments as an indicator of the work-life balance (WLB)). The increases in the risks of occupational accidents, health impairments, and decreases in WLB due to work on Sundays (coded in “no Sunday work” and “at least 1 Sunday/ month”) were calculated using analysis of variance and logistic regression models, controlling for potential confounders: demographic characteristics, work load intensity, autonomy, shift work, and other work schedule components (working on at least 1 Saturday, evening, and/or night per month, and the usual number of weekly working hours).