Children's participation in health care improves outcomes, yet little is known about factors that affect participation. We examine how child age and parental education affect participation. Visit videotapes were coded to reflect key visit tasks: information giving, information gathering, and relationship building. Multivariable models were used to analyze how participation was associated with child age and parental education. For each year of child age, physicians did 3% more information gathering, incidence rate ratio (IRR) = 1.03, 95% confidence interval (95% CI) = 1.01-1.06, but reduced relationship building by 4%, IRR = 0.96, 95% CI = 0.94-0.97. Children of college-graduate parents spoke twice as much information-giving talk, IRR = 2.11, 95% CI = 1.07-4.17, and nearly 5 times as much relationship-building talk, IRR = 4.74, 95% CI = 1.45-15.52, as children with less educated parents. Results suggest physicians might attend to relationship building with older children and work to improve participation of children of less educated parents.