To assess whether there is increased risk of tuberculous infection in children who traveled to or had a household visitor from a country having a high prevalence of tuberculosis, we conducted a case-control study. Children younger than 6 yr of age who had a tuberculin skin test read at public health clinics in areas of California that have a high prevalence of tuberculosis were enrolled. Of the 953 children who had a skin test read, 72 (7.6%) had a positive reaction. By multiple logistic regression analysis, children who had traveled in the 12 mo before the skin test were 3.9 times more likely to have a positive skin test than were children who had not traveled (95% confidence interval [CI], 1.9 to 7.9). Among children born in the United States, those who had traveled were 4.7 times more likely to have a positive skin test (95% CI, 2.0 to 11.2). Children who had a household visitor from a country having a high prevalence of tuberculosis were 2.4 times more likely to have a positive skin test than were those who did not have a visitor (95% CI, 1.0 to 5.5). These data indicate that travel to a country that has a high prevalence of tuberculosis or having a visitor from such countries increase the risk of tuberculous infection among young children. Physicians and tuberculosis control programs should incorporate questions about travel and visitors into their evaluations, and children with a history of extended travel should have a tuberculin skin test.