Two-thirds of the public would walk on by if they saw a group of teenagers drinking and verbally abusing passers-by in the street, a survey suggests.
Only 6% of the 1,784 people in England, Wales and Scotland surveyed by YouGov said they would definitely intervene. A further 21% said they probably would.
Think tank Policy Exchange commissioned the survey and called for "citizen police academies" to be set up.
They could include lessons in making citizens' arrests, it said.
The survey found that, among those questioned, people from Scotland were the most likely to step in, while those in London were the least likely.
It also suggested that more than a third of adults - 36% - would be interested in attending free classes with police officers and volunteers to learn about combating anti-social behaviour and how to avoid danger when walking home alone.
A freedom of information request made by Policy Exchange for its survey and report also revealed that the number of citizens' arrests in London's Met Police area almost halved over two years, from 3,755 in 2009/2010 to 1,816 in 2011/2012.
"It's quite understandable that most people feel reluctant to be a have-a-go hero and it is important that they have the confidence to intervene and know when it is appropriate," report author Edward Boyd said.
"Citizen police academies are one way of helping the public feel more confident about their role in preventing criminal activity."
The survey suggested there was public support for other organisations, including private businesses, taking on some of the police's administrative responsibilities to free up the time of officers.
Three-quarters of those surveyed said they would support other organisations taking on IT support and administration duties, while 56% would support them answering calls from the public.
The report also calls for neighbourhood police officers to be replaced by local crime prevention officers who, in monthly meetings with police commanders, would be "held to account personally for crime levels in their area".
In August, the RSA charity - which aims to solve "social challenges" - also called for the public to be given lessons by officers and volunteers in how to defuse conflict.
But, in response, the Police Federation said officers did not have the resources to offer such training because of cuts.