This research surveys 1,024 11-16 year olds on their experiences on social networking sites and the emotional impact and strategies they use to deal with upsetting incidents online. Twenty-eight per cent of participants reported experiencing something upsetting online in the last year. Of those who were upset, 11 per cent were dealing with this on a daily basis. While most children were found to recover quickly from negative experiences, some took weeks or months to recover. The most common upsetting experience participants reported was ‘trolling’ which the authors had defined as ‘unkind comments or rumours circulated online’. A significant minority had received sexual messages, been encouraged to self-harm, or subjected to language which was violent or aggressive. Only 22 per cent of the children who were upset talked with someone else face to face about the experience. There were some key differences between the experiences of boys and girls. The authors concluded that more can be done by social networking sites to ensure that young users are safe online and that privacy and reporting mechanisms are easy for children to use.