Although childhood lead poisoning is an important health issue in the United States, it is not distributed evenly across the country. To estimate the prevalence of childhood lead poisoning in Washington State, the authors conducted a birth certificate follow-back survey of 1- to 2-year-old children. Interviewers visited participating families at their homes to conduct blood lead tests with a portable testing device. The estimated prevalence of lead poisoning for all 1- to 2-year-old children in the state was 0.9% (95% confidence interval [CI]: 0.3-2.7); for Hispanic children in central Washington, it was 3.7% (95% CI: 1.3-10.2), and their risk of lead poisoning was significantly higher than that of all other children in the state (relative risk [RR] = 5.8, 95% CI: 1.3-24.9). Lead poisoning prevalence in Washington State children is lower than the US average and is highest among Hispanic children in central Washington.