This study is one of the largest and most comprehensive publicly available sources of information on the amount and nature of media use among American youth: (1) It includes a large national sample of more than 2,000 young people from across the country; (2) It covers children from ages 8 to 18, to track changes from childhood through the transitional "tween" period, and on into the teenage years; (3) It explores a comprehensive array of media, including TV, computers, video games, music, print, cell phones, and movies; (4) It is one of the only studies to measure and account for media multitasking--the time young people spend using more than one medium concurrently; and (5) It gathers highly detailed information about young people's media behavior, including responses to an extensive written questionnaire completed by the entire sample, plus results from a subsample of approximately 700 respondents who also maintained week-long diaries recording their media use in half-hour increments. Finally, because this is the third wave of the Kaiser Family Foundation's studies of children's media use, it not only provides a detailed look at current media use patterns among young people, but also documents changes in children's media habits since the first two waves of the study, in 1999 and 2004. It is hoped that the data provided here will offer a reliable foundation for policymakers trying to craft national media policies, parents trying to do their best to stay on top of their children's media habits, and educators, advocates and public health groups that are concerned with the impact of media on youth, and want to leverage the educational and informational potential of media in young people's lives. Appended are: (1) Tables; (2) Changes in Question Wording and Structure Over Time; (3) Toplines; and (4) Sample of Media Use Diary.