For sedentary office workers, occupational sitting is a health hazard . Excessive sitting, especially prolonged sitting (i.e. sitting more than one hour) without rest is highly likely to increase the risks of metabolic syndrome, obesity, cardiovascular disease and a range of other conditions, all of which cannot even be compensated for by taking exercise [2, 3]. Peer effect is a phenomenon whereby the behavior of an individual is affected by the behavior of their peers. It has been identified in the workplace with regards to wages, absenteeism and investment decision making in recent studies [4–7]. This paper contributes to the stream of research on peer effects on sedentary office workers by proposing a model to quantify the peer effects on office workers’ break behaviors, and by exploring how individual break behaviors can be affected by peers in the same workspace. In conclusion, peer effects have been detected in offices and have proved to have a marked influence on sedentary office workers’ resting behaviors.