The purpose of this study was to test a conceptual model linking parental support and parental physical activity (PA), with children's perception of parental support and children's PA. Baseline data were drawn from the Grade 5 ACT-i-Pass community-based PA intervention conducted in London, Ontario between May and October 2014. Parent and child PA were measured using the International Physical Activity Questionnaire and Physical Activity Questionnaire for Children, respectively. Questions pertaining to parental support and children's perception of that parental support were obtained via questionnaires. We employed structural equation modeling techniques to test the conceptual model. In total, 467 boys and 469 girls were included in the study. The model provided an acceptable model fit. Child's perception of parental support for PA had a positive effect on boys' (b = 0.319) and girls' (b = 0.326) PA. Parental PA was not significantly related to child's perception of parental support for PA. However, parent reported support for PA had a significant, positive effect on child's perception of parental support for boys (b = 0.352) and girls (b = 0.584). In terms of the indirect effects, the effect of parental PA on child's PA was not statistically significant; however, as expected, parental support for PA had a statistically significant indirect effect on child PA level in both groups. The findings of this study demonstrate the importance of children's perceptions of parental support in relation to their PA behaviours. Developing a better understanding of factors related to children's PA and identifying determinants and mediators of activity behaviours will help inform PA interventions.