By way of a case study on the regulatory role of owners and managers of brothels and rented rooms for prostitution, this study focuses on the strategies deployed by a municipality to govern these intermediaries. The analysis is based on a typology of responsibilization distinguishing between who the responsible should govern (themselves or others) and forms of power (repressive or facilitative). The regulator concomitantly renders these entrepreneurs responsible for their own possible criminal conduct (self-governing) and empowers them to keep out traffickers and pimps and to control sex-workers (others-governing). Moreover, the municipality applies both repressive and facilitative power. Although the responsibilization strategy succeeds in having entrepreneurs govern themselves, it also unintentionally undermines sex-workers’ independence and favors the largest entrepreneurs. Our study enriches the regulator intermediary target model by showing how varied and contentious the interactions between regulators and involuntary intermediaries are and by demonstrating the power game that the responsibilization strategy entails.