ObjectiveTo (a) reduce the total amount of television viewing to which preschool children are exposed; and (b) shift the balance of exposure away from commercial television toward educational content. MethodRandomized controlled clinical trial. Data collected in 2007; analyzed 2008–2011. Participants were 67 English-speaking families in Seattle with a preschool-aged child exposed to more than 90min of television viewing on average per day. A case manager for each group used in-person conferences, monthly newsletters, and e-mail contact to motivate behavior change around child television viewing (intervention) or child safety (control). ResultsCompared to those in the control group, families randomized to the intervention group experienced a significant reduction by 37minutes/day in total viewing time (95% CI: 5.6–68.7), including a marginally significant reduction by 29minutes/day in viewing of commercial content (95% CI: −4.6–63). Compared to those in the control group, those in the intervention group experienced a positive change in outcome expectations. There were no significant changes in self-efficacy or volitional control. An advance in stage-of-change was marginally significant. ConclusionsTargeting commercial TV viewing may prove a successful behavioral intervention to achieve public health goals in this population.