One in five 10-12 year olds with a social media account has been bullied online, according to a Newsround survey.
The survey, carried out by Comres, found that nearly eight out of ten 10-12 year olds in the UK has at least one social media account.
This is despite the fact that many networks say you have to be 13 to join.
The survey asked over a thousand 10-18 year olds in the UK about their experiences on social media.
Snapchat wouldn't speak to Newsround about the survey.
Instagram wouldn't do an interview but told us: "Keeping the community safe on Instagram is our number one priority and we spend a lot of time thinking about it... we require anyone on Instagram to be over the age of 13".
YouTube wouldn't do an interview either, but stressed that the site is for people aged 13 and over.
And Facebook said they'd be happy to do an interview as long as we didn't ask them about under 13s, which we wouldn't agree to.