Loads of you use social networking websites to keep in touch with your friends, upload photos and play games.
But one in five eight to 12-year-olds are ignoring the rules and signing up for sites made for much older kids and adults, according to a survey by Ofcom.
To use most social websites like Facebook, Bebo and MySpace you're supposed to be at least a teenager.
It's not against the law, but if the people in charge of the sites find out they will delete your profile.
Advice about using social sites
The people who run the websites say that the age limit is in place is to protect you from danger online.
Ofcom, who keep a check on what is shown on TV, radio, and the internet, also found that some of you don't have the right privacy settings on your page.
That means that anyone can access your personal information.