A large number of people have been arrested and one man charged over the supply of drugs at the V Festival in Chelmsford.
The two-day event at Hylands Park, which ends later, is patrolled by Essex Police.
Officers said a large number of people are in custody and a man has been charged with possession of class A drugs with intent to supply.
He is due to appear before magistrates on Monday.
Police said there had been no safety problems, but a number of other crimes had been reported, including minor assaults and thefts from tents.
About 20 cars have been seized because the drivers had committed offences including having no insurance, police added.
Ch Insp Mark Schofield said: "The majority of the crowd is having a good time but there is a very small minority who spoil things for others and we will make sure they are removed from the festival."