Children and young people encounter a range of risks on the internet relating to communication. Making friends online has attracted particular attention as a risky behaviour, especially when this leads to offline meetings, as has giving out personal information online. This article, based on the 'UK Children Go Online' survey, seeks to explain the online communication of 9-19-year-olds in terms of their offline socio-psychological characteristics (shyness, life satisfaction, risk-taking), family communication patterns and online behaviour/skills. Findings show that older teens engage in more online communication activities than do younger children and so encounter more communication risks. Although girls communicate more on the internet, this seems not to put them more at risk. It was found that children's offline social psychological characteristics, particularly their levels of life satisfaction and risk-taking, influence their online communication, with different online communication activities being predicted by different patterns of off- and online characteristics. There are weak indications that, in families which have a more conversational style of communication, teens may take fewer risks online, including a lower likelihood of meeting online friends offline. Multiple regression analyses show that those children and teens who are less satisfied with their lives and who have become more frequent and skilled internet users are more likely to value the internet as a communicative environment in which they feel more confident than they do offline, particularly in relation to the potential for anonymous communication. Since this in turn leads some into risky activities, the implications for research and policy are discussed.