Some 14,000 people in 48 countries filled in questionnaires about casual sex and how many people they expected to sleep with in the next five years.
The results were turned into an index of 'sociosexuality' - a measure of how sexually liberal people are in thought and behaviour.
Most individuals scored between 4 and 65. Finland came highest, with an average of 51. Britain's average score was 40, placing it 11th - a result linked to the decline of religious scruples, the growth of equal rights for women and a highly sexualised popular culture.
The researchers behind the study say high scores such as Britain's may be linked to the way society is increasingly willing to accept sexual promiscuity among women as well as men.
They also believe that, among certain age groups and at certain times, men and women are equally liberal.
The researchers say that cultural developments have meant women are now as able to engage in no-strings sex as men.
"Historically we have repressed women's short-term mating and there are all sorts of double standards out there where men's short-term mating was sort of acceptable but women's wasn't," Times Online quoted David Schmitt, a professor of psychology at Bradley University, Illinois, who oversaw the research, as saying.
Promiscuity Rankings Of Major Countries:
1 United Kingdom
4 Czech Republic