Background: The incidence of COVID-19 in children, defined by RT-PCR, is relatively low. Paediatric SARS-CoV-2 seropositivity studies may better estimate a history of COVID-19 in children and thus facilitate understanding of transmission risk factors. Methods: We invited 8-13-year-old children from the Edmonton area to participate in a longitudinal SARS-CoV-2 seropositivity study. At baseline, parents completed a questionnaire regarding their child’s frequency of behaviours to prevent SARS-CoV-2 transmission and exposure (e.g. wearing masks and avoiding gatherings of > 10 people) from March 2020 in addition to measurement of their child’s SARS-CoV-2 nucleocapsid IgG levels (Abbott Architect). IgG≥0·8 were considered likely seropositive. We present the interim results from the first 2 months of the study (August to October 2020) examining predictors of being likely seropositive. Findings: We recruited 565 children with a mean age of 10·5 years (SD 1·6). None reported a positive SARS-CoV-2 RT-PCR result prior to recruitment. Nine children (1·6%) were likely seropositive. Children who did not wear a mask (never, rarely, occasionally) had a 4·2% (5/118) prevalence of being likely seropositive versus 0·9% (4/423) likely seropositive for children who often or always wore their mask (p