A report by the Charities Aid Foundation (CAF), which promotes charitable giving and provides financial services to not-for-profit organisations, has highlighted a gulf in society between those who do the most for good causes and those who make a minimal contribution.
The foundation said just 9% of people give 66% of the overall time and money donated to charities - a group the organisation described as the country's "civic core".
Just over two-thirds, 67%, are in the "middle ground" of giving, accounting for the remaining 34% of charitable activity. But some 24% do little or nothing for charity - and are branded by the CAF as "zero givers".
The report aims to spark a debate about ways to make Britain more generous.
John Low, chief executive of the CAF, said: "This report raises serious questions about the nature of society in 21st-century Britain.
"Britain is one of the most charitable countries in the world, yet this research shows a stark divide in society between those who do the most for good causes and those who do little if anything at all.
"It is a worrying fact that nearly one in four people do very little if anything to support charities, which are at the forefront of civil society."