Groucho Marx once quipped: "These are my principles. If you don't like them I have others." To what extent can such a cynical sentiment be extended to the principle of Environmental Policy Integration? The principle is both longstanding, with a debut in the Single European Act (1987), and still important enough today to be carried over into the Treaty of Lisbon (2007), at Article 11 TEU. However, in practice it has proven rather difficult to make the principle of environmental policy integration legally operative, and much of the current focus has shifted towards climate policy integration (CPI) rather than the wider original principle. This paper presents some of the initial findings of the Irish EPA funding EPIIC project (Environmental Policy Integration-Innovation and Change) while also offering a critical analyses of how the EPI principle is increasingly being made legally operative via requirements for reporting, evaluation and auditing.