ACER is the 'Agency for the Cooperation of Energy Regulators'. ACER plays a key role in the integration of the EU’s markets in electricity and natural gas, providing a framework at EU level for national regulators to cooperate and providing clarity and regulatory certainty.

ACER complements and coordinates the work of the NRAs, at EU level. Its competences include preparing Framework Guidelines which will form the basis of EU-wide network codes (drafted by the European Network bodies); taking binding individual decisions on terms and conditions for access and operational security for cross border infrastructure if NRAs cannot agree; giving advice on various energy-related issues to the European institutions; and monitoring and reporting to the European Parliament and the Council.