Social media, such as Twitter and Facebook have quickly become a crucial part of everyday life, particularly for young people. The digital footprint left by users of social media presents an opportunity to study daily activities and interactions with others, without the need to burden participants with lengthy data collection methods. So far, research on social media has used random samples of unknown participants, which makes it difficult to understand who is using social media, and impossible to estimate how the use of social media might impact on mental health and wellbeing. What is needed is social media data collected on a large cohort study with years worth of data on participants. This will allow us to accurately measure who is using social media, and how they are using it as part of their daily lives. In addition, collecting social media alongside measures of wellbeing will allow us to estimate the pros and cons of social media use for mental health and wellbeing.