The website may be best known as a way to arrange nostalgic reunions with old schoolmates and reignite long-forgotten classroom romances. But for senior academics at London University's Institute of Education it has proved an invaluable research tool.
Professors Sally Power, Geoff Whitty and Tony Edwards had been following the careers of 600 educationally promising young people since they started secondary school in 1982. But when they came to write their latest report they had problems finding them.
"Tracing proved enormously challenging," the professors wrote. "Not only were our respondents highly mobile, many of their parents had moved, changed names and telephone numbers.
"Although we had always anticipated using new technologies to help the tracing, we found the Friends Reunited website more useful than expected.
It is school specific, cohort-based, cheap and quick, members tend to use their original names, it overcomes geographical distance and can often be used to identify siblings who can act as intermediaries."
Approaching young people via the site was "potentially less intrusive" than other forms of tracing.
However, Friends Reunited has drawbacks, including the fact that only full members could receive their e-mails.
"In addition, because messages are sent out 'into the ether', it is difficult to know whether non-response indicates unwillingness to participate," they said.
The team concluded that there was a closer connection between a young person's earnings and attendance at an independent school than whether they went to a prestigious university.