This chapter looks at the role of supreme audit institutions (SAIs) in supporting policy implementation and its key functions: co-ordination and communication, budget execution, implementation and enforcement of regulatory policy and the exercise of internal controls and risk management. In this stage of the policy cycle, SAIs are active in carrying out traditional activities, such as audits of budgetary processes or compliance with policies. This chapter explores opportunities and limitations for SAIs to integrate value-for-money criteria into such activities. The discussion is supported by examples from SAIs that have developed initiatives and products in this area that cut across both sectors and line entities. This chapter explains how SAIs can offer a unique overarching perspective in support of policy implementation to help decision makers spot trends and understand trade-offs.