Children as young as 14 are being recruited to run drugs for dealers, a charity has said.
Some drug dealers earn as much as £7,500 a week
The Joseph Rowntree Foundation said dealers were not always working in deprived sink estates, but often thrived in close-knit communities.
It suggested dealers sometimes ran their operation as a "family business".
It concluded the police alone could never solve the UK's drug problem, and communities at a local level must stop young people getting involved.
'Deprived but cohesive'
The report found hard drugs such as heroin and crack were on offer 24 hours a day, seven days a week.
It found recruitment of youngsters to deliver drugs may be on the increase; they were heavily used in one unnamed area as lookouts.
Dealers who do not use drugs earn up to £7,500 a week
Dealers who take drugs, and drug couriers, earn an average £450 a week
Source: Joseph Rowntree Foundation
"Professionals in another area reported youths as young as 14 working shifts to sell drugs," it said.
Dealers who did not use drugs themselves made as much as £7,500 a week profit.
Dealers who used drugs, and the drug runners, were reported to earn an average of £450 a week.
The report found widespread concern in communities about the violence, intimidation and damage to the areas' reputation caused by the criminal trade in drugs.
But the business was often controlled by well-established local families whose activities, although illegal, brought money into the area.
Co-author Professor Mike Hough said fragmented, socially disorganised neighbourhoods provided a suitable setting for an active drugs market.
"We found that drug dealing was sometimes run by cohesive groups with local family ties and extensive local networks of friends."
He found the community tolerated dealers who had grown up within it.
"The areas where that happened were very deprived areas. Their strong sense of community helped them cope with deprivation," he said. "That provided fertile ground for drug markets to evolve.
"The solution isn't simply a policing solution but you have to tackle the underlying deprivation.
"This is a complex of factors: 30 years ago there were no class A drug markets in deprived areas to speak of."
The report was looking at the relationship between dealers and local communities in four different areas of the UK.
About 70 dealers, 800 residents and 120 police and other professionals were interviewed by experts from King's College London.