Children spend more time than ever using screens — increasingly on portable digital media devices like tablets and smartphones, but our understanding about how these devices impact health is lagging. This project proposes to uncover how patterns of digital media use are formed and maintained and examine how those patterns predict mental health and cardiovascular health risk over time. The novel forms of media measurement used in this project – including passive mobile sampling, ecological momentary assessment and accelerometry – will allow us to uncover the unique and complex ways in which digital media impacts health behaviors.