The European Emissions Trading Scheme (EU ETS) is a crucial climate change policy for delivering substantial emission reductions in Member States across the EU. A ‘cap’ is defined as the total number of emission allowances given to installations for each EU ETS Member State. A high cap means a greater number of allowances are issued and therefore higher CO2 emissions permitted. A lower (tighter) cap means a lower number of allowances are issued, and therefore lower CO2 emissions. The caps determine how much installations will need to reduce and manage their emissions. The purpose of this paper is to quantify the level of ‘cap’ for key countries in the second phase of the EU ETS, to ensure the Scheme’s environmental effectiveness. The paper will provide cap levels for six key Member States: Germany, UK, Poland, Italy, Spain and the Netherlands.