We agree with Lezama et al. that the mental health of a parent may influence child behavior. Several family-level factors, including poor maternal mental health, have been demonstrated to pose a risk for behavioral problems in infancy and early childhood ( Maggi et al. 2010 ). In our study, we had information on self-reported maternal mental health problems during pregnancy, and we adjusted for this covariate in the analysis. In response to the letter by Lezama et al. and to further assess this covariate we have conducted a sensitivity analysis in which we excluded women with mental health problems ( n = 491). Exclusion of these women did not change the results of our study on either the total difficulties score (adjusted odds ration [OR] = 1.07; 95% confidence interval [CI]: 1.00, 1.14, compared with OR = 1.07; 95% CI: 1.00, 1.14 before exclusion) or the hyperactivity/inattention subscale (adjusted OR = 1.11; 95% CI: 1.03, 1.18, compared with adjusted OR = 1.10; 95% CI: 1.03, 1.18 before exclusion). This suggests that the associations between exposure to residential road traffic noise in early childhood and child behavior problems were not driven by maternal mental health problems.