How much television should young people watch, and how important are the health effects of watching too much? So few study members watched no television that we are unable to define a safe limit below which there were no health effects. Children and adolescents who watched 1 h or less a day were the healthiest (figure), although not many were in this group (30 [5·7%] male study members, 39 [7·9%] female study members). The American Academy of Pediatrics recommends that parents limit their child’s viewing to 2 h per day.2 About half of study members during childhood and more than two-thirds of those during adolescence exceeded this limit on weekdays. If we assume a causal association between child and adolescent television viewing and adult health, calculations of population-attributable fractions indicate that exceeding the 2 h limit might be responsible for 17% of overweight, 15% of poor fitness, 15% of raised serum cholesterol, and 17% of smoking at age 26 years.