The aims of this study were to develop a measure, the Role Modelling of Body Image (Attitudes and Behaviors) Questionnaire (RMBI-Q), to determine maternal perceptions of their body image role modelling in front of their children, and to evaluate how role modelling differs with demographic characteristics to identify characteristics of mothers who may require assistance in being a positive role model. Participants were a community-based sample of 887 mothers who provided demographic information and completed the RMBI-Q, Body Appreciation Scale (BAS-2), and a measure of dietary restraint (DEBQ) in an online questionnaire. Exploratory factor analysis revealed one 7-item factor for the RMBI-Q. Confirmatory factor analysis revealed that removal of an item was necessary for model fit, and thus, a 6-item version of the RMBI-Q was evaluated. Good internal consistency, test-retest reliability, content validity, and convergent validity were found. Higher scores on the RMBI-Q correlated with greater maternal body appreciation and lower dietary restraint. More positive role modelling was reported by mothers with lower body mass index and younger children. The RMBI-Q is useful for assessing maternal modelling of positive behaviors that may improve children's body image. Findings highlight avenues for body image interventions for mothers.