Physical activity and sedentary behavior (performed primarily while sitting) play a key role in the current and future health of young people. Most health evidence and intervention strategies targeting reductions in children's sedentary behavior have focused on television viewing, with mixed evidence as to the effectiveness of these strategies and of the importance of television viewing for children's health. Evidence from studies with adults using objective measures of sedentary behavior suggests that accumulated sedentary time is independently associated with metabolic health; importantly, emerging evidence suggests that the manner in which the sedentary behavior is accrued (ie, frequency of interruptions to time spent sedentary) may also have independent effects on health. Potential novel intervention approaches to reduce children's sedentary time include activity breaks during class time at school, delivery of active lessons and homework, and changes to the classroom environment. Further evidence of the importance of sedentary time (both total accumulation and frequency of interruptions) on children's health is required. Future studies should assess the effectiveness of interventions targeting organizational and pedagogical changes in schools as well as using homework to engage with families in more active ways.