The group hope their shocking "Did you do it?" posters will make litter bugs think again. They feature a website address with terrible images of hurt animals.
Over 69,000 animals were treated for injuries caused by rubbish last year.
One dog had its tongue cut off by broken glass and a baby hedgehog was strangled by a plastic bag.
But the group say teenagers will only pick up their rubbish if they are paid to do it or bribed with a day off school.
Don't feel guilty
They say their research shows:
The report also says young people can't be bothered with bins because they are dirty and smelly.
- Teens think their schools are swamped with rubbish
- Teachers don't punish people for dropping litter because they do it too
- Most common things dropped are crisp packets, sweet
wrappers, bits of paper, cans, cigarette ends and gum
- Litter lessons were "boring".