Background: There is increasing uptake of workplace physical activity programs to prevent chronic disease. While they are frequently evaluated for improvement in biomedical risk factors there has been little evaluation of additional benefits for psychosocial health. We aimed to evaluate whether participation in a four-month, team-based, pedometer-based workplace health program known to improve biomedical risk factors is associated with an improvement in well-being, immediately after the program and eight-months after program completion. Methods. At baseline (2008), 762 adults (aged 40 ? 10 SD years, 42 male) employed in primarily sedentary occupations and voluntarily enrolled in a physical activity program were recruited from ten Australian worksites. Data was collected at baseline, at the completion of the four-month program and eight-months after program completion. The outcome was the WHO-Five Well-being Index (WHO-5), a self-administered five-item scale that can be dichotomised as poor (less than 52 ) or positive (more than or equal to 52 ) well-being. Results: At baseline, 75 of participants had positive well-being (mean: 60 ? 19 SD WHO-5 units). On average, well-being improved immediately after the health program (+3.5 units, p <0.001) and was sustained eight-months later (+3.4 units from baseline, p <0.001). In the 25 with poor well-being at baseline, 49.5 moved into the positive well-being category immediately after program completion, sustained eight-months later (p <0.001). Conclusions: Clinically relevant immediate and sustained improvements in well-being were observed after participation in the health program. These results suggest that participation in workplace programs, such as the one evaluated here, also has the potential to improve well-being.