Forty-four people were arrested at Saturday's Raggamuffin music festival in Rotorua, which this year had a liquor ban for the first time.
Police say the majority of offenders were young people who deliberately chose to defy the ban at city's International Stadium.
Mobile CCTV cameras were used, and police were stationed at the venue's entry points.
The event was attended by more than 30,000 people - more than half the population of Rotorua.
Police Area Commander, Inspector Bruce Horne, says the event and law enforcement operation went very smoothly.