Background: There is a growing trend of preloading with alcohol before entering entertainment districts. It is claimed that this occurs to save money and that preloading may be a good indicator of harmful drinking and risk taking behaviours more generally. No study has collected data from a large sample as the participants entered entertainment districts and measured blood alcohol concentration (BAC) levels and self-reported drinking and risk taking behaviours in a systematic way. Methods: In this research, police and academics worked together to gauge the breadth and depth of preloading behaviours. In all, 3039 people completed a questionnaire and were breathalysed as they entered entertainment districts in Queensland, Australia. Of those, 2751 represented people from Brisbane and this data, collected every Thursday night to Sunday morning during the warm months, was analysed. Results: More than 79% of people reported to preload and 71% returned a BAC greater than zero, both with little difference between the genders. Of preloaders, the mean BAC was 0.071, with ‘to socialise with friends’ being the primary reason given for preloading. Increasing preloading BAC was related to increasing risk taking and antisocial behaviours, as well as alcohol abuse and dependence. Older people entering entertainment districts had more accurate estimates of their BAC, yet 20% of our sample did not understand how the BAC system worked. Conducting the research was associated with a higher access rate to police and a lower arrest rate in the areas of data collection in comparison to the same nights 1 year earlier. Conclusion: Preloading is widespread and involves moderate to heavy drinking in the Australian population visiting entertainment districts. Any interventions to curb drinking behaviours and reduce violence in night time entertainment districts need to involve approaches aimed at cultural phenomena, such as preloading behaviours.