Objectives: Excessive 'screen time' has been associated with a range of psychosocial disturbances and increasing pediatric obesity. This study describes the magnitude, distribution, composition and time-distribution of children's screen use; examines correlates of screen use; and characterises 'extreme' screen users (top quartile). Methods: 1,039 South Australian children aged 10-13 years old completed a multimedia 24-hour activity recall diary on 2-4 occasions in 2002, including at least one school day and one non-school day. Results: The median screen time was 229 minutes.d(-1). This was higher in boys (264 vs. 196 minutes; p < 0.001) and on non-school days (260 vs. 190 minutes; p < 0.001), increased with age (p=0.003), and decreased with socio-economic status (SES; p=0.003). Television consumed 73% of all screen time, video games 19%, non-game computer use 6%, and cinema 2%. The top quartile of screen users were more likely to be boys (OR=3., have low physical activity (OR=4.3), spend > 25% of screen time playing video games (OR=1., sleep less, and be of lower SES. Conclusions and Implications: Interventions to reduce screen time should target inactive, low-SES boys, encourage earlier bedtimes, and limit video game use.