Objectives: To assess the effects of an intervention in a worksite setting on changes in physical activity. It was expected that an intervention with an emphasis on daily life activities, such as brisk walking, would increase the proportion of individuals expending more than 1000 kcal per week in activities with at least moderate intensity, or influence individuals to change from one stage of the Transtheoretical Model of Behaviour to a higher one.Design: Quasi-experimental. Data were collected before and after a 4 month intervention period in 6 offices (n=211) of the Swiss federal administration. Two offices (n=168) served as controls.Methods: Participants completed a 7 day recall questionnaire on physical activities (daily life activities, leisure time activities, and sport) and stages of readiness for change, along with questions on demographic variables. Components of the intervention programme were: information, actions for daily life activities, fitness lessons, and counselling.Results: Between precontemplation/contemplation, preparation, and action/maintenance there was a significant difference of more than 850 kcal of energy expenditure. Baseline and follow-up examinations revealed a significant progression across the stages of change in the intervention offices. Subgroup analyses showed that the level of physical activity at baseline influenced the effect of the intervention. Exclusively in worksites with a lower proportion of sufficiently active individuals, the intervention was able to substantially increase the proportion by 21%.Conclusions: A diversified intervention programme in a worksite setting encourages participants to become more physically active during work and leisure time.