The interpretation of administrative policies is of great importance in contemporary public law. The correct approach to policy interpretation has, however, been subject to insufficient academic scrutiny. The effect of policies is to provide guidance: not only to decision-makers, but also to stakeholders in the decision. Obvious stakeholders include the applicant or the individual who is the subject of the administrative decision, but the scope of potential legitimate stakeholders may go far beyond this. In matters of general interest, the broader public may be guided by policy (for instance, whether to object to a proposal during a consultation exercise, or on what basis to object). When considering how policy should be interpreted, the court should have regard to the extent of the appropriate audience of the policy, specifically considering how the least expert reader of the policy would interpret it. This ‘least expert reader principle’ will assist in answering difficult questions, such as whether the court should have regard to the underlying evidence base when interpreting a policy. The courts should rely upon, and express their reasoning by reference to, the least expert reader principle, in order to increase the transparency of judgments in the field of policy interpretation.