['To assess whether socioeconomic inequalities were already present in preschool children.', "We used data from 2954 Dutch children participating in a longitudinal birth cohort study. Indicators of socioeconomic status were mother's educational level and household income. Body mass index (BMI)-for-age standard deviation scores were derived from a national reference. Overweight was defined at 24 and 36 months according to age- and sex-specific cut-off points for BMI. Multivariable regression analyses were performed.", 'Relative to children from mothers with the highest educational level, mean BMI standard deviation scores was lower at age 24 months in children from mothers with the low, mid-low, and mid-high educational level, and in the mid-low group at 36 months (P < .001). Prevalence of overweight was lower in children from mothers with the mid-low educational level at age 24 and 36 months (adjusted odds ratio at 24 months: 0.61; 95% confidence interval: 0.43-0.87 and at 36 months: 0.65; 95% confidence interval: 0.44-0.96) but was not significantly different for the other educational levels. There were no significant differences in childhood overweight by income level.'] Is socioeconomic status inversely associated with overweight in preschool children?