['To identify modifiable risk factors for obesity among low socioeconomic status (LSES) children.', 'Cross-sectional data were obtained from 238 4-7-year-old children and 224 mothers from LSES preschools. Anthropometric measurements were obtained; mothers were interviewed about sociodemographic characteristics, health behaviors, perceptions and beliefs.', "The combined prevalence of overweight and obesity (OWOB) among children was 29.8% based on the new World Health Organization (WHO) growth standard. Prevalence of OWOB (body mass index ≥25) among mothers was 51.8%. Mean age, sleeping hours, gender distribution and poverty level were similar between normal and OWOB children. Over 82% of mothers underestimated their child's weight status. Of the 62 OWOB children, 74.2% were perceived by their mothers as having 'normal weight' (NW) and 8% were perceived as 'thin'. Mothers perceived 67 out of 158 NW children (42.4%) as 'thin' (P<0.001). Mediation analysis indicated that 10% of the effect of maternal underestimation on child's OWOB may be mediated through child's daily sedentary hours (P=0.06). In a multivariable logistic-regression analysis controlling for maternal obesity, knowledge regarding breakfast's importance and child's daily sedentary hours, maternal underestimation of the child's weight status (odds ratio=7.33; 95% confidence interval (CI):2.41-22.37; P<0.0001) and parental smoking (odds ratio=3.25; 95% CI: 1.26-8.40; P=0.015) were the only significant factors associated with OWOB in LSES children."] Are maternal weight misperceptions and smoking associated with overweight and obesity in low SES preschoolers?