This paper studies the spread of compliance behaviour in neighbourhood networks involving over 500,000 households in Austria. The authors exploit random variation from a field experiment which varied the content of mailings sent to potential evaders of TV license fees. The data reveal a strong treatment spillover: ‘untreated’ households, who were not part of the experimental sample, are more likely to switch from evasion to compliance in response to the mailings received by their network neighbours. The authors analyse the spillover within a model of communication in networks based on DeGroot (1974). Consistent with the model, they find that: (i) the spillover increases with the treated households’ eigenvector centrality; and (ii) local concentration of equally treated households produces a lower spillover. These findings carry important implications for enforcement policies.