Despite widespread discussion in the United States, up until now there has not been a review of the demographic and contextual factors associated with Canadian academic achievement. Using Arksey and O'Malley's (2005) framework, a scoping review was conducted to answer two questions: What demographic and contextual factors are most commonly used in K-12 academic achievement studies in Canada? What, if any, research gaps exist? Fifty-four studies were identified for review. The results reveal 40 demographic or contextual factors, with socio-economic status (SES), gender, language factors, immigrant status, family structure, and Indigenous status being the most commonly studied. Race, religion, and LGBTQ+ identity were understudied factors. The authors recommend the adoption of "educational opportunity gap" as a consistent research term, identify understudied factors, and outline several research design considerations.