Abstract Background Despite the sale of alcohol to drunk people being illegal in the UK, high levels of intoxication and alcohol-related harms remain common in nightlife environments. In 2013, a study of bar servers' propensity to serve alcohol to drunks was undertaken and found that 84% of purchase attempts by pseudo-intoxicated actors resulted in the sale of alcohol. Following presentation of these findings to local partners, the Drink Less Enjoy More multi-component intervention was designed and implemented to address drunkenness in the nighttime economy by: increasing awareness of legislation; supporting bar staff compliance with the law; and promoting responsible drinking amongst nightlife users. Methods. Pre- (n=214) and post- (n=202) intervention nightlife patron surveys were conducted which explored: drinking behaviours; expectations of drunkenness; and knowledge of the law. Bar staff surveys examined bar server practice, awareness of legislation and perceptions of the intervention. Finally, 100 pre- and post-intervention alcohol test purchase attempts using pseudo-intoxicated actors were made to evaluate the impact of the intervention on service of alcohol to drunks. Results From pre- to-post intervention there was a significant increase in nightlife user knowledge of the laws around the service of alcohol to drunks (from 45% to 66%) and the purchasing alcohol for a drunk friend (33%-55%). The majority of bar staff perceived the intervention as having had a positive impact on their serving practices. Crucially, there was a significant reduction in the proportion of alcohol test purchases leading to a sale of alcohol to a pseudo-intoxicated actor (84%-26%). Conclusions Findings from the intervention are positive suggesting since the intervention was implemented nightlife user knowledge of the laws around the service of alcohol to drunks has significantly increased, and crucially the service of alcohol to pseudo-intoxicated actors has reduced substantially. Funding Liverpool City Council