A study by a Nova Scotia police force found teenagers shared personal information and photos of themselves with total strangers while online.
Truro police say their five-week study shows social networking sites are an "unsupervised playground."
During the study, local university students created fictitious profiles and used passive means to add 296 friends between the ages of 12 and 17.
Under police supervision, the students posed as teenagers who moved to the region and accessed a fan page of a local school they said they would be attending in September.
Only two people said they couldn't add them as friends because their parents monitored their social networking activities.
Const. Todd Taylor of the force's community enhancement division calls the findings "astounding."