This article concerns recent challenges to the utility of “accessory liability” as an organising principle or concept in private law and argues that accessory liability is a coherent body of law with common features that is worthy of separate, holistic treatment. We defend a conceptual framework for accessory liability which is dynamic in its operation and which does not dictate the precise legal content of accessory liability in different contexts. Such a conception of accessory liability has come under challenge from recent cases and commentary which either minimise the scope and analytical relevance of accessory liability altogether in equity and tort law or propound a conceptual framework for accessory liability that is fixed in its application and uniform in its content across the whole of private law. Our purpose in this article is to resist both the dismissal, and simplification, of accessory liability in private law.