The purpose of this study was to identify characteristics associated with maternal concerns for her child becoming overweight, and how these concerns are related to her perceptions of her child's weight. A school-based sample of 55 children and their mothers from Houston, Texas, participated in a cross-sectional survey. Mothers reported on their concerns and perceptions regarding their child's weight. Child and mother height and weight were directly assessed to calculate body mass index (BMI). Covariate-adjusted logistic regression models were conducted. Over one-third of mothers misperceived their child's weight status [9% (n = 5) overestimated; 27% (n = 15) underestimated]. Mothers of sons were less accurate compared with mothers of daughters. For every one unit increase in maternal BMI, mothers had 13% higher odds of being concerned of their child becoming overweight. Concerned mothers had 82% lower odds of underestimating their child's weight. In order for school-based childhood obesity prevention and intervention programs to be successful, parents must accurately perceive their elementary school-age child's weight status. School nurses can be vital to these efforts through proper training and resources. Nurses can use the "School Nurse Childhood Obesity Toolkit" and motivational interviewing techniques to address parental concerns and perceptions prior to teaching behavior modification strategies to children/families.