Nine out of 10 girls aged 14 and 15 claim to have suffered depression, with 6% saying life was "not worth living", a poll for Bliss magazine has found.
One fifth of girls said they had no-one to talk to about problems
Top sources of stress were the pressure to look good (94%), school work (84%), bullying (67%) and broken homes (52%).
Almost a third said they had harmed themselves, usually because they were "confused" or "no-one was listening", and 15% had binged on drink and drugs.
The Stressed and Depressed? survey polled 2,000 girls aged 14 and 15.
Just 32% said they felt "greatly loved" by their parents, and two thirds said they thought life was emotionally easier when their parents were young.
Some 30% revealed they drank alcohol every week, mainly to make themselves feel better.
Almost 20% said they had no-one to talk to about problems, while 68% said their friends were "the only ones who will listen".
Bliss editor Lisa Smosarski said: "Teenage girls are expected to cope with a cocktail of broken homes, endless school work, emotional pressures and the availability of drink and drugs.
"It's a cocktail that is seriously damaging the psyche of teenage girls."
She added: "Many parents now treat their children as their 'best friends', whereas most teenagers want a solid mother and father figure.
"Most parents are oblivious to the damage being done to their children."