Purpose: To investigate how breastfeeding initiation and duration affect the likelihood of being overweight and obese in children aged 2 to 5. Design: Cross-sectional data from the 2003 National Survey of Children's Health. Setting: Rural and urban areas of the United States. Subjects: Households where at least one member was between the ages of 2 and 5 (sample size 8207). Measures: Parent-reported body mass index, breastfeeding initiation and duration, covariates (gender, family income and education, ethnicity, child care attendance, maternal health and physical activity, residential area). Analysis: Partial proportional odds models. Results: In early childhood, breastfed children had 5.3% higher probability of being normal weight (p = .002) and 8.9% (p < .001) lower probability of being obese compared to children who had never been breastfed. Children who had been breastfed for less than 3 months had 3.1% lower probability of being normal weight (p = .013) and 4.7% higher probability of being obese (p = .013) with respect to children who had been breastfed for 3 months and above. Conclusion: Study findings suggest that length of breastfeeding, whether exclusive or not, may be associated with lower risk of obesity in early childhood. However, caution is needed in generalizing results because of the limitations of the analysis. Based on findings from this study and others, breastfeeding promotion policies can cite the potential protective effect that breastfeeding has on weight in early childhood.