Suitable execution of moderation policy is challenging but crucial for the trustworthiness and credibility of internal high-stakes assessment systems. In formal education, policies are rarely implemented as intended. Instead, they are "enacted" in ways influenced by mediating factors including the internal and external contexts of organisations. Ball, Maguire and Braun's (2012) contextual-dimensions heuristic provides a conceptualisation of organisation-specific contexts, which is useful when the organisation is the unit of analysis. However, comprehensive analysis of policy enactment--including that relating to moderation--warrants consideration of contexts narrower in scope than whole organisations and wider in scope than individual organisations. In this article, we modify Ball and colleagues' heuristic, incorporating Biggs' (1993) application of systems theory, to develop a new contextual framework for moderation that is applicable on multiple scales and enables such analysis. This framework is applied to a selection of contemporary moderation studies with scopes that vary from one course, to jurisdiction-wide, to illustrate its utility. Our framework captures the hierarchy of embedded, interacting systems within which moderation is enacted and makes contextual relationships visible, allowing consideration of perspectives between units of analysis. Our framework provides a nuanced conceptualisation of context that distinguishes between "material" and "human" factors, and "intrinsic" and "extrinsic" contexts. We present potential uses of the framework for education organisations, central agencies and researchers including as a tool for identifying contextual factors involved in executing moderation initiatives and identifying possible pressures, tensions and enablers.