Social Behaviour in Work Absence*

By making use of a large‐scale randomized experiment, we test whether social behaviour is important for work absence due to illness. The individuals treated in the experiment were exposed to less monitoring of their eligibility to collect sickness insurance benefits, which sharply increased their non‐monitored work absence. This exogenous variation is exploited in two complementary analyses. In both analyses, we find significant social‐behaviour effects. Using detailed data, we conclude that the social‐behaviour effects most likely stem from fairness concerns.